










                         SENDMAILTM

              INSTALLATION AND OPERATION GUIDE

                        Eric Allman
                       Claus Assmann
                    Gregory Neil Shapiro
                      Proofpoint, Inc.

                       Version 8.759

                 For Sendmail Version 8.15




     SendmailTM implements a  general  purpose  internetwork
mail  routing  facility  under the UNIX(R) operating system.
It is not tied to any one transport protocol -- its function
may  be likened to a crossbar switch, relaying messages from
one domain into another.  In the process, it can do  a  lim-
ited  amount  of  message  header editing to put the message
into a format that is appropriate for the receiving  domain.
All  of  this  is  done under the control of a configuration
file.

     Due to the requirements of  flexibility  for  sendmail,
the  configuration  file  can  seem somewhat unapproachable.
However, there are only a few basic configurations for  most
sites, for which standard configuration files have been sup-
plied.  Most other configurations can be built by  adjusting
an existing configuration file incrementally.

     Sendmail  is  based  on  RFC 821 (Simple Mail Transport
Protocol), RFC 822 (Internet Mail Headers Format),  RFC  974
(MX  routing),  RFC  1123  (Internet Host Requirements), RFC
1413 (Identification server), RFC 1652 (SMTP 8BITMIME Exten-
sion),  RFC  1869  (SMTP Service Extensions), RFC 1870 (SMTP
SIZE Extension), RFC 1891 (SMTP  Delivery  Status  Notifica-
tions), RFC 1892 (Multipart/Report), RFC 1893 (Enhanced Mail
System Status Codes), RFC 1894  (Delivery  Status  Notifica-
tions),  RFC 1985 (SMTP Service Extension for Remote Message
Queue  Starting),  RFC  2033  (Local  Message   Transmission
____________________
   DISCLAIMER: This documentation is under modification.
   Sendmail  is  a  trademark of Proofpoint, Inc.  US Patent
Numbers 6865671, 6986037.




Sendmail Installation and Operation Guide           SMM:08-1







SMM:08-2           Sendmail Installation and Operation Guide


Protocol),  RFC  2034  (SMTP Service Extension for Returning
Enhanced Error Codes), RFC 2045 (MIME),  RFC  2476  (Message
Submission),  RFC  2487  (SMTP  Service Extension for Secure
SMTP over TLS), RFC 2554 (SMTP Service Extension for Authen-
tication),  RFC  2821  (Simple  Mail Transfer Protocol), RFC
2822 (Internet Message Format), RFC 2852  (Deliver  By  SMTP
Service Extension), and RFC 2920 (SMTP Service Extension for
Command Pipelining).  However, since sendmail is designed to
work in a wider world, in many cases it can be configured to
exceed these protocols.  These cases are described herein.

     Although sendmail is intended to run without  the  need
for monitoring, it has a number of features that may be used
to monitor or adjust the  operation  under  unusual  circum-
stances.  These features are described.

     Section  one  describes  how to do a basic sendmail in-
stallation.  Section two explains the day-to-day information
you should know to maintain your mail system.  If you have a
relatively normal site, these two  sections  should  contain
sufficient  information for you to install sendmail and keep
it happy.  Section three has information regarding the  com-
mand line arguments.  Section four describes some parameters
that may be  safely  tweaked.   Section  five  contains  the
nitty-gritty information about the configuration file.  This
section is for masochists and people who  must  write  their
own configuration file.  Section six describes configuration
that can be done at compile time.   The  appendixes  give  a
brief  but  detailed explanation of a number of features not
described in the rest of the paper.

































Sendmail Installation and Operation Guide           SMM:08-7


1.  BASIC INSTALLATION

        There are two basic steps  to  installing  sendmail.
   First,  you  have  to compile and install the binary.  If
   sendmail has already been ported to your operating system
   that should be simple.  Second, you must build a run-time
   configuration file.  This is a file that  sendmail  reads
   when  it  starts  up  that describes the mailers it knows
   about, how to parse addresses, how to rewrite the message
   header,  and  the  settings of various options.  Although
   the configuration file can be quite complex, a configura-
   tion can usually be built using an M4-based configuration
   language.  Assuming you have the standard  sendmail  dis-
   tribution, see cf/README for further information.

        The  remainder of this section will describe the in-
   stallation of sendmail assuming you can use  one  of  the
   existing  configurations  and that the standard installa-
   tion parameters are acceptable.  All pathnames and  exam-
   ples  are  given  from  the root of the sendmail subtree,
   normally /usr/src/usr.sbin/sendmail on 4.4BSD-based  sys-
   tems.

        Continue  with  the next section if you need/want to
   compile sendmail yourself.  If you have a running  binary
   already  on your system, you should probably skip to sec-
   tion 1.2.

   1.1.  Compiling Sendmail

           All sendmail source is in the sendmail  subdirec-
      tory.  To compile sendmail, "cd" into the sendmail di-
      rectory and type

          ./Build

      This will leave the binary in an  appropriately  named
      subdirectory, e.g., obj.BSD-OS.2.1.i386.  It works for
      multiple object versions compiled out of the same  di-
      rectory.

      1.1.1.  Tweaking the Build Invocation

              You  can give parameters on the Build command.
         In most cases these are only used  when  the  obj.*
         directory   is  first  created.   To  restart  from
         scratch, use -c.  These commands include:

         -L libdirs
              A list of directories to search for libraries.

         -I incdirs
              A list of directories to  search  for  include










SMM:08-8           Sendmail Installation and Operation Guide


              files.

         -E envar=value
              Set  an  environment  variable to an indicated
              value before compiling.

         -c   Create a new obj.*  tree before running.

         -f siteconfig
              Read the indicated  site  configuration  file.
              If  this parameter is not specified, Build in-
              cludes    all    of    the    files    $BUILD-
              TOOLS/Site/site.$oscf.m4      and      $BUILD-
              TOOLS/Site/site.config.m4,  where  $BUILDTOOLS
              is  normally ../devtools and $oscf is the same
              name as used on the obj.*  directory.  See be-
              low  for  a description of the site configura-
              tion file.

         -S   Skip  auto-configuration.   Build  will  avoid
              auto-detecting  libraries if this is set.  All
              libraries and map definitions must  be  speci-
              fied in the site configuration file.

         Most  other  parameters are passed to the make pro-
         gram; for details see $BUILDTOOLS/README.

      1.1.2.  Creating a Site Configuration File

              (This section is not yet complete.   For  now,
         see  the  file  devtools/README  for details.)  See
         sendmail/README for various compilation flags  that
         can be set.

      1.1.3.  Tweaking the Makefile

              Sendmail  supports  two  different formats for
         the local (on disk) version of  databases,  notably
         the aliases database.  At least one of these should
         be defined if at all possible.

         NDBM      The  ``new  DBM''  format,  available  on
                   nearly  all  systems  around today.  This
                   was the preferred format prior to 4.4BSD.
                   It allows such complex things as multiple
                   databases and closing  a  currently  open
                   database.

         NEWDB     The  Berkeley  DB  package.   If you have
                   this, use it.  It  allows  long  records,
                   multiple  open  databases, real in-memory
                   caching, and so forth.   You  can  define
                   this in conjunction with NDBM; if you do,










Sendmail Installation and Operation Guide           SMM:08-9


                   old alias databases are read, but when  a
                   new  database  is  created  it will be in
                   NEWDB format.  As a nasty  hack,  if  you
                   have NEWDB, NDBM, and NIS defined, and if
                   the alias file  name  includes  the  sub-
                   string  "/yp/", sendmail will create both
                   new and old versions of  the  alias  file
                   during  a  newalias command.  This is re-
                   quired  because  the  Sun  NIS/YP  system
                   reads  the DBM version of the alias file.
                   It's ugly as sin, but it works.

         If neither of these are defined, sendmail reads the
         alias  file  into memory on every invocation.  This
         can be slow and should be avoided.  There are  also
         several methods for remote database access:

         LDAP      Lightweight Directory Access Protocol.

         NIS       Sun's  Network Information Services (for-
                   merly YP).

         NISPLUS   Sun's NIS+ services.

         NETINFO   NeXT's NetInfo service.

         HESIOD    Hesiod service (from Athena).

         Other compilation  flags  are  set  in  conf.h  and
         should be predefined for you unless you are porting
         to a new environment.  For more options  see  send-
         mail/README.

      1.1.4.  Compilation and installation

              After  making  the  local system configuration
         described above, You should be able to compile  and
         install the system.  The script "Build" is the best
         approach on most systems:

             ./Build

         This will use uname(1) to create a custom  Makefile
         for your environment.

              If  you are installing in the standard places,
         you should be able to install using

             ./Build install

         This should install the  binary  in  /usr/sbin  and
         create    links    from   /usr/bin/newaliases   and
         /usr/bin/mailq  to  /usr/sbin/sendmail.   On   most










SMM:08-10          Sendmail Installation and Operation Guide


         systems  it will also format and install man pages.
         Notice: as of version 8.12 sendmail will no  longer
         be  installed  set-user-ID root by default.  If you
         really want to use the old method, you can  specify
         it as target:

             ./Build install-set-user-id


   1.2.  Configuration Files

           Sendmail  cannot  operate without a configuration
      file.  The configuration  defines  the  mail  delivery
      mechanisms  understood  at  this  site,  how to access
      them, how to forward email to remote mail systems, and
      a  number  of  tuning  parameters.  This configuration
      file is detailed in the later portion  of  this  docu-
      ment.

           The  sendmail  configuration  can  be daunting at
      first.  The world is complex, and the mail  configura-
      tion  reflects  that.   The  distribution  includes an
      m4-based configuration package that hides a lot of the
      complexity.  See cf/README for details.

           Our  configuration  files  are processed by m4 to
      facilitate local customization; the  directory  cf  of
      the   sendmail  distribution  directory  contains  the
      source files.  This directory contains several  subdi-
      rectories:

      cf        Both site-dependent and site-independent de-
                scriptions of hosts.  These can  be  literal
                host  names  (e.g.,  "ucbvax.mc")  when  the
                hosts are gateways or more general  descrip-
                tions  (such  as  "generic-solaris2.mc" as a
                general  description  of  an  SMTP-connected
                host  running Solaris 2.x.  Files ending .mc
                (``M4 Configuration'')  are  the  input  de-
                scriptions; the output is in the correspond-
                ing .cf  file.   The  general  structure  of
                these files is described below.

      domain    Site-dependent    subdomain    descriptions.
                These are tied to the way your  organization
                wants  to  do  addressing.  For example, do-
                main/CS.Berkeley.EDU.m4 is  our  description
                for  hosts in the CS.Berkeley.EDU subdomain.
                These are referenced  using  the  DOMAIN  m4
                macro in the .mc file.

      feature   Definitions  of  specific features that some
                particular host in  your  site  might  want.










Sendmail Installation and Operation Guide          SMM:08-11


                These  are  referenced  using the FEATURE m4
                macro.  An example  feature  is  use_cw_file
                (which    tells    sendmail   to   read   an
                /etc/mail/local-host-names file  on  startup
                to find the set of local names).

      hack      Local  hacks,  referenced  using the HACK m4
                macro.  Try to avoid these.   The  point  of
                having  them  here  is to make it clear that
                they smell.

      m4        Site-independent m4(1)  include  files  that
                have information common to all configuration
                files.  This can be thought of  as  a  "#in-
                clude" directory.

      mailer    Definitions of mailers, referenced using the
                MAILER m4 macro.  The mailer types that  are
                known  in  this distribution are fax, local,
                smtp, uucp, and usenet.  For example, to in-
                clude  support  for  the UUCP-based mailers,
                use "MAILER(uucp)".

      ostype    Definitions  describing  various   operating
                system environments (such as the location of
                support files).  These are referenced  using
                the OSTYPE m4 macro.

      sh        Shell  files  used  by the m4 build process.
                You shouldn't have to mess with these.

      siteconfig
                Local UUCP connectivity  information.   This
                directory  has  been supplanted by the mail-
                ertable  feature;  any  new   configurations
                should  use  that  feature  to  do UUCP (and
                other) routing.  The use of  this  directory
                is deprecated.

           If you are in a new domain (e.g., a company), you
      will probably want to create a cf/domain file for your
      domain.   This consists primarily of relay definitions
      and features you want enabled site-wide: for  example,
      Berkeley's domain definition defines relays for BitNET
      and UUCP.  These are specific to Berkeley, and  should
      be   fully-qualified   internet-style   domain  names.
      Please check to make certain they are  reasonable  for
      your domain.

           Subdomains  at  Berkeley  are also represented in
      the cf/domain  directory.   For  example,  the  domain
      CS.Berkeley.EDU  is  the  Computer  Science subdomain,
      EECS.Berkeley.EDU is the  Electrical  Engineering  and










SMM:08-12          Sendmail Installation and Operation Guide


      Computer  Sciences  subdomain, and S2K.Berkeley.EDU is
      the Sequoia 2000 subdomain.  You will probably have to
      add  an  entry to this directory to be appropriate for
      your domain.

           You will have to use or create .mc files  in  the
      cf/cf  subdirectory  for your hosts.  This is detailed
      in the cf/README file.

   1.3.  Details of Installation Files

           This subsection describes the files that comprise
      the sendmail installation.

      1.3.1.  /usr/sbin/sendmail

              The   binary   for   sendmail  is  located  in
         /usr/sbin[1].  It should be set-group-ID  smmsp  as
         described  in sendmail/SECURITY.  For security rea-
         sons, /, /usr, and /usr/sbin  should  be  owned  by
         root, mode 0755[2].

      1.3.2.  /etc/mail/sendmail.cf

              This  is the main configuration file for send-
         mail[3].  This is one of the two  non-library  file
         names  compiled  into  sendmail[4],  the  other  is
         /etc/mail/submit.cf.

              The configuration file is normally created us-
         ing the distribution files described above.  If you
         have a particularly  unusual  system  configuration
____________________
   [1]This is usually /usr/sbin on 4.4BSD and newer systems;
many  systems install it in /usr/lib.  I understand it is in
/usr/ucblib on System V Release 4.
   [2]Some  vendors  ship  them owned by bin; this creates a
security hole that is  not  actually  related  to  sendmail.
Other  important  directories  that  should have restrictive
ownerships  and  permissions  are  /bin,   /usr/bin,   /etc,
/etc/mail, /usr/etc, /lib, and /usr/lib.
   [3]Actually, the pathname varies depending on the operat-
ing system; /etc/mail is the preferred directory.  Some old-
er systems install it in /usr/lib/sendmail.cf, and I've also
seen  it in /usr/ucblib.  If you want to move this file, add
-D_PATH_SENDMAILCF=\"/file/name\" to the flags passed to the
C compiler.  Moving this file is not recommended: other pro-
grams and scripts know of this location.
   [4]The system libraries can  reference  other  files;  in
particular,  system  library subroutines that sendmail calls
probably reference /etc/passwd and /etc/resolv.conf.












Sendmail Installation and Operation Guide          SMM:08-13


         you may need to create a special version.  The for-
         mat of this file is detailed in later  sections  of
         this document.

      1.3.3.  /etc/mail/submit.cf

              This  is  the  configuration file for sendmail
         when it is used for  initial  mail  submission,  in
         which case it is also called ``Mail Submission Pro-
         gram'' (MSP) in contrast to ``Mail Transfer Agent''
         (MTA).   Starting  with version 8.12, sendmail uses
         one of two different configuration files  based  on
         its  operation  mode  (or  the new -A option).  For
         initial mail submission, i.e., if one  of  the  op-
         tions  -bm (default), -bs, or -t is specified, sub-
         mit.cf is used (if available), for other operations
         sendmail.cf is used.  Details can be found in send-
         mail/SECURITY.  submit.cf is shipped with  sendmail
         (in  cf/cf/)  and  is  installed  by  default.   If
         changes to the configuration need to be made, start
         with  cf/cf/submit.mc and follow the instruction in
         cf/README.

      1.3.4.  /usr/bin/newaliases

              The newaliases command should just be  a  link
         to sendmail:

             rm -f /usr/bin/newaliases
             ln -s /usr/sbin/sendmail /usr/bin/newaliases

         This  can  be installed in whatever search path you
         prefer for your system.

      1.3.5.  /usr/bin/hoststat

              The hoststat command should just be a link  to
         sendmail, in a fashion similar to newaliases.  This
         command lists the status of the last mail  transac-
         tion  with all remote hosts.  The -v flag will pre-
         vent the status display from being  truncated.   It
         functions  only when the HostStatusDirectory option
         is set.

      1.3.6.  /usr/bin/purgestat

              This command is also a link to  sendmail.   It
         flushes  expired  (Timeout.hoststatus)  information
         that is stored in the HostStatusDirectory tree.














SMM:08-14          Sendmail Installation and Operation Guide


      1.3.7.  /var/spool/mqueue

              The directory /var/spool/mqueue should be cre-
         ated to hold the mail queue.  This directory should
         be mode 0700 and owned by root.

              The actual path of this directory  is  defined
         by  the  QueueDirectory  option  of the sendmail.cf
         file.  To use multiple queues, supply a value  end-
         ing     with    an    asterisk.     For    example,
         /var/spool/mqueue/qd* will use all of the  directo-
         ries  or  symbolic  links  to directories beginning
         with `qd' in /var/spool/mqueue  as  queue  directo-
         ries.   Do not change the queue directory structure
         while sendmail is running.

              If these directories  have  subdirectories  or
         symbolic links to directories named `qf', `df', and
         `xf', then these will be  used  for  the  different
         queue  file  types.   That  is,  the data files are
         stored in the  `df'  subdirectory,  the  transcript
         files  are stored in the `xf' subdirectory, and all
         others are stored in the `qf' subdirectory.

              If shared memory support is compiled in, send-
         mail  stores  the  available  diskspace in a shared
         memory segment to make the values readily available
         to  all children without incurring system overhead.
         In this case, only the  daemon  updates  the  data;
         i.e., the sendmail daemon creates the shared memory
         segment and deletes it if it is terminated.  To use
         this, sendmail must have been compiled with support
         for shared memory (-DSM_CONF_SHM)  and  the  option
         SharedMemoryKey  must  be  set.  Notice: do not use
         the same key for sendmail invocations with  differ-
         ent queue directories or different queue group dec-
         larations.  Access to shared  memory  is  not  con-
         trolled  by  locks, i.e., there is a race condition
         when data in the shared memory  is  updated.   How-
         ever,  since operation of sendmail does not rely on
         the data in the shared memory, this does not  nega-
         tively influence the behavior.

      1.3.8.  /var/spool/clientmqueue

              The  directory  /var/spool/clientmqueue should
         be created to hold the mail queue.  This  directory
         should  be mode 0770 and owned by user smmsp, group
         smmsp.

              The actual path of this directory  is  defined
         by the QueueDirectory option of the submit.cf file.











Sendmail Installation and Operation Guide          SMM:08-15


      1.3.9.  /var/spool/mqueue/.hoststat

              This  is a typical value for the HostStatusDi-
         rectory option, containing one file per  host  that
         this  sendmail  has  chatted  with recently.  It is
         normally a subdirectory of mqueue.

      1.3.10.  /etc/mail/aliases*

              The    system    aliases    are    held     in
         "/etc/mail/aliases".   A  sample is given in "send-
         mail/aliases" which  includes  some  aliases  which
         must be defined:

             cp sendmail/aliases /etc/mail/aliases
             edit /etc/mail/aliases

         You  should  extend this file with any aliases that
         are apropos to your system.

              Normally sendmail looks at a database  version
         of      the     files,     stored     either     in
         "/etc/mail/aliases.dir" and "/etc/mail/aliases.pag"
         or  "/etc/mail/aliases.db" depending on which data-
         base package you are using.   The  actual  path  of
         this file is defined in the AliasFile option of the
         sendmail.cf file.

              The permissions of  the  alias  file  and  the
         database  versions  should be 0640 to prevent local
         denial of service attacks as explained in  the  top
         level  README in the sendmail distribution.  If the
         permissions  0640  are  used,  be  sure  that  only
         trusted users belong to the group assigned to those
         files.  Otherwise, files should not even  be  group
         readable.

      1.3.11.  /etc/rc or /etc/init.d/sendmail

              It  will be necessary to start up the sendmail
         daemon when your system reboots.  This daemon  per-
         forms  two functions: it listens on the SMTP socket
         for connections (to receive mail from a remote sys-
         tem) and it processes the queue periodically to in-
         sure that mail gets delivered when hosts come up.

              If  necessary,  add  the  following  lines  to
         "/etc/rc"  (or  "/etc/rc.local"  as appropriate) in
         the area where it is starting up the daemons  on  a
         BSD-base  system,  or on a System-V-based system in
         one    of    the    startup    files,     typically
         "/etc/init.d/sendmail":











SMM:08-16          Sendmail Installation and Operation Guide


             if [ -f /usr/sbin/sendmail -a -f /etc/mail/sendmail.cf ]; then
                  (cd /var/spool/mqueue; rm -f xf*)
                  /usr/sbin/sendmail -bd -q30m &
                  echo -n ' sendmail' >/dev/console
             fi

         The  "cd"  and  "rm" commands insure that all tran-
         script files have been  removed;  extraneous  tran-
         script  files may be left around if the system goes
         down in the middle of processing  a  message.   The
         line  that actually invokes sendmail has two flags:
         "-bd" causes it to listen on  the  SMTP  port,  and
         "-q30m" causes it to run the queue every half hour.

              Some people use a more complex startup script,
         removing zero length qf/hf/Qf files  and  df  files
         for  which there is no qf/hf/Qf file.  Note this is
         not advisable.  For example, see Figure  1  for  an
         example  of  a complex script which does this clean
         up.

      1.3.12.  /etc/mail/helpfile

              This is the help file used by  the  SMTP  HELP
         command.   It should be copied from "sendmail/help-
         file":

             cp sendmail/helpfile /etc/mail/helpfile

         The actual path of this  file  is  defined  in  the
         HelpFile option of the sendmail.cf file.

      1.3.13.  /etc/mail/statistics

              If  you  wish to collect statistics about your
         mail  traffic,   you   should   create   the   file
         "/etc/mail/statistics":

             cp /dev/null /etc/mail/statistics
             chmod 0600 /etc/mail/statistics

         This  file  does  not grow.  It is printed with the
         program "mailstats/mailstats.c."  The  actual  path
         of  this  file  is  defined  in the S option of the
         sendmail.cf file.

      1.3.14.  /usr/bin/mailq

              If sendmail is invoked  as  "mailq,"  it  will
         simulate  the  -bp  flag (i.e., sendmail will print
         the contents of the mail queue; see  below).   This
         should be a link to /usr/sbin/sendmail.











Sendmail Installation and Operation Guide          SMM:08-17



____________________________________________________________

#!/bin/sh
# remove zero length qf/hf/Qf files
for qffile in qf* hf* Qf*
do
     if [ -r $qffile ]
     then
          if [ ! -s $qffile ]
          then
               echo -n " <zero: $qffile>" > /dev/console
               rm -f $qffile
          fi
     fi
done
# rename tf files to be qf if the qf does not exist
for tffile in tf*
do
     qffile=`echo $tffile | sed 's/t/q/'`
     if [ -r $tffile -a ! -f $qffile ]
     then
          echo -n " <recovering: $tffile>" > /dev/console
          mv $tffile $qffile
     else
          if [ -f $tffile ]
          then
               echo -n " <extra: $tffile>" > /dev/console
               rm -f $tffile
          fi
     fi
done
# remove df files with no corresponding qf/hf/Qf files
for dffile in df*
do
     qffile=`echo $dffile | sed 's/d/q/'`
     hffile=`echo $dffile | sed 's/d/h/'`
     Qffile=`echo $dffile | sed 's/d/Q/'`
     if [ -r $dffile -a ! -f $qffile -a ! -f $hffile -a ! -f $Qffile ]
     then
          echo -n " <incomplete: $dffile>" > /dev/console
          mv $dffile `echo $dffile | sed 's/d/D/'`
     fi
done
# announce files that have been saved during disaster recovery
for xffile in [A-Z]f*
do
     if [ -f $xffile ]
     then
          echo -n " <panic: $xffile>" > /dev/console
     fi
done











SMM:08-18          Sendmail Installation and Operation Guide


            Figure 1 -- A complex startup script
____________________________________________________________


      1.3.15.  sendmail.pid

              sendmail  stores  its  current pid in the file
         specified  by  the  PidFile  option   (default   is
         _PATH_SENDMAILPID).    sendmail  uses  TempFileMode
         (which defaults to 0600) as the permissions of that
         file  to prevent local denial of service attacks as
         explained in the top level README in  the  sendmail
         distribution.   If the file already exists, then it
         might be necessary to change  the  permissions  ac-
         cordingly, e.g.,

             chmod 0600 /var/run/sendmail.pid

         Note that as of version 8.13, this file is unlinked
         when sendmail exits.  As a result of this change, a
         script such as the following, which may have worked
         prior to 8.13, will no longer work:

             # stop & start sendmail
             PIDFILE=/var/run/sendmail.pid
             kill `head -1 $PIDFILE`
             `tail -1 $PIDFILE`

         because it assumes that the pidfile will still  ex-
         ist  even  after  killing  the  process to which it
         refers.  Below is a script  which  will  work  cor-
         rectly on both newer and older versions:

             # stop & start sendmail
             PIDFILE=/var/run/sendmail.pid
             pid=`head -1 $PIDFILE`
             cmd=`tail -1 $PIDFILE`
             kill $pid
             $cmd

         This is just an example script, it does not perform
         any error checks, e.g., whether the pidfile  exists
         at all.

      1.3.16.  Map Files

              To  prevent local denial of service attacks as
         explained in the top level README in  the  sendmail
         distribution,  the permissions of map files created
         by makemap should be 0640.  The use of 0640 implies
         that  only  trusted  users  belong to the group as-
         signed to those files.  If those files already  ex-
         ist,  then  it  might  be  necessary  to change the










Sendmail Installation and Operation Guide          SMM:08-19


         permissions accordingly, e.g.,

             cd /etc/mail
             chmod 0640 *.db *.pag *.dir


2.  NORMAL OPERATIONS

   2.1.  The System Log

           The system log is  supported  by  the  syslogd(8)
      program.   All messages from sendmail are logged under
      the LOG_MAIL facility[5].

      2.1.1.  Format

              Each  line  in  the  system  log consists of a
         timestamp, the name of the machine  that  generated
         it  (for logging from several machines over the lo-
         cal area network), the word "sendmail:", and a mes-
         sage[6].   Most  messages   are   a   sequence   of
         name=value pairs.

              The  two  most  common lines are logged when a
         message is processed.  The first logs  the  receipt
         of  a  message;  there will be exactly one of these
         per message.  Some fields may be omitted if they do
         not contain interesting information.  Fields are:

         from      The envelope sender address.

         size      The size of the message in bytes.

         class     The  class  (i.e., numeric precedence) of
                   the message.

         pri       The initial message  priority  (used  for
                   queue sorting).

         nrcpts    The  number  of  envelope  recipients for
                   this message (after aliasing and forward-
                   ing).

         msgid     The  message  id of the message (from the
                   header).

____________________
   [5]Except on Ultrix, which does not support facilities in
the syslog.
   [6]This  format  may  vary  slightly  if  your vendor has
changed the syntax.












SMM:08-20          Sendmail Installation and Operation Guide


         bodytype  The message body type (7BIT or 8BITMIME),
                   as determined from the envelope.

         proto     The protocol used to receive this message
                   (e.g., ESMTP or UUCP)

         daemon    The daemon name  from  the  DaemonPortOp-
                   tions setting.

         relay     The machine from which it was received.

         There  is also one line logged per delivery attempt
         (so there can be several per message if delivery is
         deferred or there are multiple recipients).  Fields
         are:

         to        A comma-separated list of the  recipients
                   to this mailer.

         ctladdr   The  ``controlling  user'',  that is, the
                   name of the user whose credentials we use
                   for delivery.

         delay     The  total  delay  between  the time this
                   message was received and the current  de-
                   livery attempt.

         xdelay    The  amount of time needed in this deliv-
                   ery attempt (normally indicative  of  the
                   speed of the connection).

         mailer    The name of the mailer used to deliver to
                   this recipient.

         relay     The name of the host  that  actually  ac-
                   cepted (or rejected) this recipient.

         dsn       The  enhanced  error  code  (RFC 2034) if
                   available.

         stat      The delivery status.

         Not all fields are present in all messages; for ex-
         ample,  the  relay  is usually not listed for local
         deliveries.

      2.1.2.  Levels

              If you have syslogd(8) or  an  equivalent  in-
         stalled,  you will be able to do logging.  There is
         a large amount of information that can  be  logged.
         The  log is arranged as a succession of levels.  At
         the lowest level only extremely strange  situations










Sendmail Installation and Operation Guide          SMM:08-21


         are  logged.   At  the highest level, even the most
         mundane and uninteresting events are  recorded  for
         posterity.   As  a convention, log levels under ten
         are considered generally "useful;" log levels above
         64  are  reserved  for  debugging purposes.  Levels
         from 11-64 are  reserved  for  verbose  information
         that some sites might want.

              A  complete  description  of the log levels is
         given in section ``Log Level''.

   2.2.  Dumping State

           You can ask sendmail to log a dump  of  the  open
      files and the connection cache by sending it a SIGUSR1
      signal.  The results are logged at LOG_DEBUG priority.

   2.3.  The Mail Queues

           Mail messages may either be delivered immediately
      or  be  held  for  later  delivery.  Held messages are
      placed into a holding directory called a mail queue.

           A mail message may be queued for these reasons:

       + If a mail message is temporarily undeliverable,  it
         is  queued and delivery is attempted later.  If the
         message is addressed to multiple recipients, it  is
         queued  only  for those recipients to whom delivery
         is not immediately possible.
       + If the SuperSafe option is set to  true,  all  mail
         messages are queued while delivery is attempted.
       + If  the DeliveryMode option is set to queue-only or
         defer, all mail is queued, and no immediate  deliv-
         ery is attempted.
       + If  the  load average becomes higher than the value
         of the QueueLA option and the QueueFactor  (q)  op-
         tion  divided by the difference in the current load
         average and the QueueLA option  plus  one  is  less
         than  the  priority  of  the  message, messages are
         queued rather than immediately delivered.
       + One or more addresses are marked as  expensive  and
         delivery  is  postponed until the next queue run or
         one or more address are marked as held  via  mailer
         which uses the hold mailer flag.
       + The mail message has been marked as quarantined via
         a mail filter or rulesets.

      2.3.1.  Queue Groups and Queue Directories

              There are one or more mail queues.  Each  mail
         queue  belongs to a queue group.  There is always a
         default  queue  group  that  is  called  ``mqueue''










SMM:08-22          Sendmail Installation and Operation Guide


         (which  is where messages go by default unless oth-
         erwise specified).  The  directory  or  directories
         which  comprise  the default queue group are speci-
         fied by the QueueDirectory option.  There are  zero
         or  more additional named queue groups declared us-
         ing the Q command in the configuration file.

              By default, a queued message is placed in  the
         queue  group associated with the first recipient in
         the recipient list.  A recipient address is  mapped
         to  a queue group as follows.  First, if there is a
         ruleset called ``queuegroup'', and if this  ruleset
         maps  the  address to a queue group name, then that
         queue group is chosen.  That is, the  argument  for
         the ruleset is the recipient address and the result
         should be $# followed by the name of a queue group.
         Otherwise,  if  the  mailer associated with the ad-
         dress specifies a  queue  group,  then  that  queue
         group  is  chosen.   Otherwise,  the  default queue
         group is chosen.

              A message with  multiple  recipients  will  be
         split  if  different queue groups are chosen by the
         mapping of recipients to queue groups.

              When a message is placed in a queue group, and
         the queue group has more than one queue, a queue is
         selected randomly.

              If  a  message  with  multiple  recipients  is
         placed into a queue group with the 'r' option (max-
         imum number of recipients per  message)  set  to  a
         positive  value N, and if there are more than N re-
         cipients in the message, then the message  will  be
         split into multiple messages, each of which have at
         most N recipients.

              Notice: if multiple queue groups are used,  do
         not move queue files around, e.g., into a different
         queue directory.  This may have weird  effects  and
         can  cause  mail  not to be delivered.  Queue files
         and directories should be  treated  as  opaque  and
         should not be manipulated directly.

      2.3.2.  Queue Runs

              sendmail has two different ways to process the
         queue(s).  The first one is to start queue  runners
         after certain intervals (``normal'' queue runners),
         the second one is to keep  queue  runner  processes
         around  (``persistent'' queue runners).  How to se-
         lect either of these types is discussed in the  ap-
         pendix  ``COMMAND  LINE  FLAGS''.  Persistent queue










Sendmail Installation and Operation Guide          SMM:08-23


         runners have the advantage that  no  new  processes
         need  to be spawned at certain intervals; they just
         sleep for a specified time after  they  finished  a
         queue  run.   Another advantage of persistent queue
         runners is that only one  process  belonging  to  a
         workgroup  (a  workgroup  is a set of queue groups)
         collects the data for a queue run and then multiple
         queue  runner  may  go ahead using that data.  This
         can significantly reduce the disk I/O necessary  to
         read  the queue files compared to starting multiple
         queue runners directly.  Their disadvantage is that
         a  new  queue  run  is only started after all queue
         runners belonging to a group finished their  tasks.
         In  case one of the queue runners tries delivery to
         a slow recipient site at the end of  a  queue  run,
         the  next  queue  run may be substantially delayed.
         In general this should be smoothed out due  to  the
         distribution of those slow jobs, however, for sites
         with small number of queue entries this  might  in-
         troduce  noticable  delays.  In general, persistent
         queue runners are only useful for  sites  with  big
         queues.

      2.3.3.  Manual Intervention

              Under normal conditions the mail queue will be
         processed transparently.   However,  you  may  find
         that  manual  intervention  is sometimes necessary.
         For example, if a major host is down for  a  period
         of  time  the  queue  may become clogged.  Although
         sendmail ought to recover gracefully when the  host
         comes up, you may find performance unacceptably bad
         in the meantime.  In that case you  want  to  check
         the  content  of the queue and manipulate it as ex-
         plained in the next two sections.

      2.3.4.  Printing the queue

              The contents of the queue(s)  can  be  printed
         using  the  mailq command (or by specifying the -bp
         flag to sendmail):

             mailq

         This will produce a listing of the queue id's,  the
         size  of  the message, the date the message entered
         the queue,  and  the  sender  and  recipients.   If
         shared  memory support is compiled in, the flag -bP
         can be used to print the number of entries  in  the
         queue(s),  provided  a  process  updates  the data.
         However, as explained earlier, the output might  be
         slightly  wrong,  since access to the shared memory
         is not locked.  For example,  ``unknown  number  of










SMM:08-24          Sendmail Installation and Operation Guide


         entries''  might  be  shown.  The internal counters
         are updated after each queue  run  to  the  correct
         value again.

      2.3.5.  Forcing the queue

              Sendmail should run the queue automatically at
         intervals.  When using multiple queues, a  separate
         process  will  by default be created to run each of
         the queues unless the queue run is initiated  by  a
         user  with  the  verbose flag.  The algorithm is to
         read and sort the queue, and  then  to  attempt  to
         process all jobs in order.  When it attempts to run
         the job, sendmail first checks to see if the job is
         locked.  If so, it ignores the job.

              There  is  no  attempt to insure that only one
         queue processor exists at any time, since there  is
         no  guarantee  that  a  job  cannot take forever to
         process (however, sendmail does include  heuristics
         to try to abort jobs that are taking absurd amounts
         of time; technically, this violates RFC 821, but is
         blessed  by  RFC  1123).   Due to the locking algo-
         rithm, it is impossible for one job to  freeze  the
         entire  queue.  However, an uncooperative recipient
         host or a program recipient that never returns  can
         accumulate many processes in your system.  Unfortu-
         nately, there is no completely general way to solve
         this.

              In  some cases, you may find that a major host
         going down for a couple of days may create  a  pro-
         hibitively  large queue.  This will result in send-
         mail spending an inordinate amount of time  sorting
         the  queue.   This situation can be fixed by moving
         the queue to a temporary place and creating  a  new
         queue.  The old queue can be run later when the of-
         fending host returns to service.

              To do this, it is acceptable to move  the  en-
         tire queue directory:

             cd /var/spool
             mv mqueue omqueue; mkdir mqueue; chmod 0700 mqueue

         You  should then kill the existing daemon (since it
         will still be processing in the  old  queue  direc-
         tory) and create a new daemon.

              To run the old mail queue, issue the following
         command:

             /usr/sbin/sendmail -C /etc/mail/queue.cf -q










Sendmail Installation and Operation Guide          SMM:08-25


         The -C flag specifies  an  alternate  configuration
         file queue.cf which should refer to the moved queue
         directory

             O QueueDirectory=/var/spool/omqueue

         and the -q flag says to just run every job  in  the
         queue.  You can also specify the moved queue direc-
         tory on the command line

             /usr/sbin/sendmail -oQ/var/spool/omqueue -q

         but this requires that you do not have queue groups
         in  the  configuration  file, because those are not
         subdirectories of the  moved  directory.   See  the
         section  about  ``Queue Group Declaration'' for de-
         tails; you most likely need a different  configura-
         tion  file  to  correctly  deal  with this problem.
         However, a proper  configuration  of  queue  groups
         should  avoid  filling up queue directories, so you
         shouldn't run into this problem.   If  you  have  a
         tendency  toward voyeurism, you can use the -v flag
         to watch what is going on.

              When the queue is finally emptied, you can re-
         move the directory:

             rmdir /var/spool/omqueue


      2.3.6.  Quarantined Queue Items

              It  is possible to "quarantine" mail messages,
         otherwise known  as  envelopes.   Envelopes  (queue
         files)  are  stored but not considered for delivery
         or display unless the "quarantine" state of the en-
         velope  is undone or delivery or display of quaran-
         tined items is requested.  Quarantined messages are
         tagged  by  using  a  different  name for the queue
         file, 'hf' instead of 'qf', and by adding the quar-
         antine reason to the queue file.

              Delivery  or  display of quarantined items can
         be requested using the  -qQ  flag  to  sendmail  or
         mailq.  Additionally, messages already in the queue
         can be quarantined or unquarantined using  the  new
         -Q flag to sendmail.  For example,

             sendmail -Qreason -q[!][I|R|S][matchstring]

         Quarantines  the  normal  queue  items matching the
         criteria specified by the -q[!][I|R|S][matchstring]
         using the reason given on the -Q flag.  Likewise,










SMM:08-26          Sendmail Installation and Operation Guide


             sendmail -qQ -Q[reason] -q[!][I|R|S|Q][matchstring]

         Change  the  quarantine  reason for the quarantined
         items  matching  the  criteria  specified  by   the
         -q[!][I|R|S|Q][matchstring]  using the reason given
         on the -Q flag.  If there is no reason,
          unquarantine the matching items and make them nor-
         mal  queue  items.   Note  that  the -qQ flag tells
         sendmail to operate on quarantined items instead of
         normal items.

   2.4.  Disk Based Connection Information

           Sendmail  stores  a  large  amount of information
      about each remote system it has connected to  in  mem-
      ory.  It is possible to preserve some of this informa-
      tion on disk as well, by using the HostStatusDirectory
      option, so that it may be shared between several invo-
      cations of sendmail.  This allows mail  to  be  queued
      immediately or skipped during a queue run if there has
      been a recent failure in connecting to  a  remote  ma-
      chine.   Note:  information  about  a remote system is
      stored in a file whose pathname consists of the compo-
      nents  of the hostname in reverse order.  For example,
      the information  for  host.example.com  is  stored  in
      com./example./host.   For  top-level  domains like com
      this can create a large number of subdirectories which
      on  some  filesystems  can exhaust some limits.  More-
      over, the performance of  lookups  in  directory  with
      thousands  of  entries can be fairly slow depending on
      the filesystem implementation.

           Additionally  enabling  SingleThreadDelivery  has
      the  added effect of single-threading mail delivery to
      a destination.  This can be quite helpful if  the  re-
      mote  machine is running an SMTP server that is easily
      overloaded or cannot accept more than a single connec-
      tion  at  a  time,  but  can cause some messages to be
      punted to a future queue run.  It also applies to  all
      hosts, so setting this because you have one machine on
      site that runs some software that  is  easily  overrun
      can  cause  mail to other hosts to be slowed down.  If
      this option is set, you probably want to set the  Min-
      QueueAge  option as well and run the queue fairly fre-
      quently; this way jobs that are  skipped  because  an-
      other  sendmail  is  talking  to the same host will be
      tried again quickly rather than being  delayed  for  a
      long time.

           The  disk  based  host information is stored in a
      subdirectory of the  mqueue  directory  called  .host-












Sendmail Installation and Operation Guide          SMM:08-27


      stat[7].   Removing this directory and its subdirecto-
      ries has an effect similar to  the  purgestat  command
      and  is  completely safe.  However, purgestat only re-
      moves expired (Timeout.hoststatus) data.  The informa-
      tion  in  these  directories  can  be perused with the
      hoststat command, which will indicate the  host  name,
      the  last  access,  and the status of that access.  An
      asterisk in the left  most  column  indicates  that  a
      sendmail  process  currently  has  the host locked for
      mail delivery.

           The disk based connection information is  treated
      the  same  way  as memory based connection information
      for the purpose of timeouts.  By default,  information
      about host failures is valid for 30 minutes.  This can
      be adjusted with the Timeout.hoststatus option.

           The connection information stored on disk may  be
      expired  at  any time with the purgestat command or by
      invoking sendmail with the -bH switch.  The connection
      information may be viewed with the hoststat command or
      by invoking sendmail with the -bh switch.

   2.5.  The Service Switch

           The implementation  of  certain  system  services
      such as host and user name lookup is controlled by the
      service switch.  If the host operating system supports
      such  a  switch, and sendmail knows about it, sendmail
      will use the native version.  Ultrix, Solaris, and DEC
      OSF/1 are examples of such systems[8].

           If  the underlying operating system does not sup-
      port a service switch (e.g., SunOS  4.X,  HP-UX,  BSD)
      then sendmail will provide a stub implementation.  The
      ServiceSwitchFile option points to the name of a  file
      that  has  the service definitions.  Each line has the
      name of a service and the possible implementations  of
      that service.  For example, the file:

          hosts     dns files nis
          aliases   files nis

      will ask sendmail to look for hosts in the Domain Name
      System first.  If  the  requested  host  name  is  not
____________________
   [7]This is the usual value of the HostStatusDirectory op-
tion; it can, of  course,  go  anywhere  you  like  in  your
filesystem.
   [8]HP-UX  10  has  service  switch support, but since the
APIs are apparently not available in the libraries  sendmail
does not use the native service switch in this release.











SMM:08-28          Sendmail Installation and Operation Guide


      found,  it  tries  local  files,  and if that fails it
      tries NIS.  Similarly, when  looking  for  aliases  it
      will try the local files first followed by NIS.

           Notice: since sendmail must access MX records for
      correct operation, it will use DNS if it is configured
      in the ServiceSwitchFile file.  Hence an entry like

          hosts     files dns

      will not avoid DNS lookups even if a host can be found
      in /etc/hosts.

           Service switches are not  completely  integrated.
      For  example,  despite  the  fact  that the host entry
      listed in the above example specifies to look in  NIS,
      on  SunOS  this won't happen because the system imple-
      mentation of gethostbyname(3) doesn't understand this.

   2.6.  The Alias Database

           After recipient addresses are read from the  SMTP
      connection  or command line they are parsed by ruleset
      0, which must resolve to  a  {mailer,  host,  address}
      triple.   If  the flags selected by the mailer include
      the A (aliasable) flag, the address part of the triple
      is  looked up as the key (i.e., the left hand side) in
      the alias database.  If there is a match, the  address
      is  deleted  from  the send queue and all addresses on
      the right hand side of the alias are added in place of
      the  alias that was found.  This is a recursive opera-
      tion, so aliases found in the right hand side  of  the
      alias are similarly expanded.

           The alias database exists in two forms.  One is a
      text form, maintained in the  file  /etc/mail/aliases.
      The aliases are of the form

          name: name1, name2, ...

      Only local names may be aliased; e.g.,

          eric@prep.ai.MIT.EDU: eric@CS.Berkeley.EDU

      will   not   have   the   desired  effect  (except  on
      prep.ai.MIT.EDU, and they probably don't want  me)[9].
      Aliases  may be continued by starting any continuation
____________________
   [9]Actually, any mailer that has the `A' mailer flag  set
will  permit aliasing; this is normally limited to the local
mailer.












Sendmail Installation and Operation Guide          SMM:08-29


      lines with a space or a tab or by putting a  backslash
      directly  before  the  newline.  Blank lines and lines
      beginning with a sharp sign ("#") are comments.

           The second form is processed by  the  ndbm(3)[10]
      or  the Berkeley DB library.  This form is in the file
      /etc/mail/aliases.db    (if    using     NEWDB)     or
      /etc/mail/aliases.dir  and  /etc/mail/aliases.pag  (if
      using NDBM).  This is the form that sendmail  actually
      uses  to  resolve  aliases.  This technique is used to
      improve performance.

           The control of search order is  actually  set  by
      the service switch.  Essentially, the entry

          O AliasFile=switch:aliases

      is  always  added  as the first alias entry; also, the
      first alias file name without a class  (e.g.,  without
      "nis:"  on  the front) will be used as the name of the
      file for a ``files'' entry in the aliases switch.  For
      example, if the configuration file contains

          O AliasFile=/etc/mail/aliases

      and the service switch contains

          aliases   nis files nisplus

      then  aliases  will first be searched in the NIS data-
      base, then in  /etc/mail/aliases,  then  in  the  NIS+
      database.

           You  can also use NIS-based alias files.  For ex-
      ample, the specification:

          O AliasFile=/etc/mail/aliases
          O AliasFile=nis:mail.aliases@my.nis.domain

      will first search the /etc/mail/aliases file and  then
      the   map  named  "mail.aliases"  in  "my.nis.domain".
      Warning: if you build your own NIS-based alias  files,
      be  sure  to  provide the -l flag to makedbm(8) to map
      upper case letters in the keys to lower  case;  other-
      wise,  aliases  with upper case letters in their names
      won't match incoming addresses.

           Additional flags can be added after the colon ex-
      actly like a K line -- for example:
____________________
   [10]The gdbm package does not work.












SMM:08-30          Sendmail Installation and Operation Guide


          O AliasFile=nis:-N mail.aliases@my.nis.domain

      will search the appropriate NIS map and always include
      null bytes in the key.  Also:

          O AliasFile=nis:-f mail.aliases@my.nis.domain

      will prevent sendmail from downcasing the  key  before
      the alias lookup.

      2.6.1.  Rebuilding the alias database

              The hash or dbm version of the database may be
         rebuilt explicitly by executing the command

             newaliases

         This is equivalent to giving sendmail the -bi flag:

             /usr/sbin/sendmail -bi


              If you have multiple aliases databases  speci-
         fied,  the -bi flag rebuilds all the database types
         it understands (for example, it  can  rebuild  NDBM
         databases but not NIS databases).

      2.6.2.  Potential problems

              There  are a number of problems that can occur
         with the alias database.  They all  result  from  a
         sendmail process accessing the DBM version while it
         is only partially built.  This can happen under two
         circumstances:  One  process  accesses the database
         while another process  is  rebuilding  it,  or  the
         process  rebuilding the database dies (due to being
         killed or a system crash) before completing the re-
         build.

              Sendmail  has  three  techniques to try to re-
         lieve these problems.  First, it ignores interrupts
         while  rebuilding  the  database;  this  avoids the
         problem of someone aborting the process  leaving  a
         partially  rebuilt  database.  Second, it locks the
         database source file during the rebuild -- but that
         may not work over NFS or if the file is unwritable.
         Third, at the end of the rebuild it adds  an  alias
         of the form

             @: @

         (which  is  not  normally  legal).  Before sendmail
         will access the database, it checks to insure  that










Sendmail Installation and Operation Guide          SMM:08-31


         this entry exists[11].

      2.6.3.  List owners

              If an error occurs on sending to a certain ad-
         dress, say "x", sendmail will look for an alias  of
         the  form "owner-x" to receive the errors.  This is
         typically useful for a mailing list where the  sub-
         mitter  of the list has no control over the mainte-
         nance of the list itself; in  this  case  the  list
         maintainer would be the owner of the list.  For ex-
         ample:

             unix-wizards: eric@ucbarpa, wnj@monet, nosuchuser,
                  sam@matisse
             owner-unix-wizards: unix-wizards-request
             unix-wizards-request: eric@ucbarpa

         would cause "eric@ucbarpa" to get  the  error  that
         will  occur  when someone sends to unix-wizards due
         to the inclusion of "nosuchuser" on the list.

              List owners also cause the envelope sender ad-
         dress  to  be  modified.  The contents of the owner
         alias are used if they point to a single user, oth-
         erwise  the  name of the alias itself is used.  For
         this reason, and to obey Internet conventions,  the
         "owner-"  address normally points at the "-request"
         address; this causes messages to go  out  with  the
         typical  Internet  convention  of  using ``list-re-
         quest'' as the return address.

   2.7.  User Information Database

           This option is deprecated, use virtusertable  and
      genericstable  instead  as explained in cf/README.  If
      you have a version of sendmail with the user  informa-
      tion  database compiled in, and you have specified one
      or more databases using the U  option,  the  databases
      will be searched for a user:maildrop entry.  If found,
      the mail will be sent to the specified address.

   2.8.  Per-User Forwarding (.forward Files)

           As an alternative to the alias database, any user
      may  put a file with the name ".forward" in his or her
      home  directory.   If  this  file   exists,   sendmail
____________________
   [11]The AliasWait option is required in the configuration
for this action to occur.  This should  normally  be  speci-
fied.












SMM:08-32          Sendmail Installation and Operation Guide


      redirects  mail for that user to the list of addresses
      listed in the .forward file.  Note  that  aliases  are
      fully  expanded  before  forward files are referenced.
      For example, if the home directory for user "mckusick"
      has a .forward file with contents:

          mckusick@ernie
          kirk@calder

      then  any  mail  arriving for "mckusick" will be redi-
      rected to the specified accounts.

           Actually, the configuration file  defines  a  se-
      quence of filenames to check.  By default, this is the
      user's .forward file, but can be defined  to  be  more
      generally using the ForwardPath option.  If you change
      this, you will have to inform your user  base  of  the
      change;  .forward is pretty well incorporated into the
      collective subconscious.

   2.9.  Special Header Lines

           Several header lines have special interpretations
      defined by the configuration file.  Others have inter-
      pretations built into sendmail that cannot be  changed
      without  changing  the  code.  These built-ins are de-
      scribed here.

      2.9.1.  Errors-To:

              If errors occur  anywhere  during  processing,
         this  header will cause error messages to go to the
         listed addresses.  This  is  intended  for  mailing
         lists.

              The  Errors-To:  header was created in the bad
         old days when UUCP didn't understand  the  distinc-
         tion  between  an envelope and a header; this was a
         hack to provide what should now be  passed  as  the
         envelope sender address.  It should go away.  It is
         only used if the UseErrorsTo option is set.

              The Errors-To: header is officially deprecated
         and will go away in a future release.

      2.9.2.  Apparently-To:

              RFC  822 requires at least one recipient field
         (To:, Cc:, or Bcc: line) in every  message.   If  a
         message  comes  in with no recipients listed in the
         message then sendmail will adjust the header  based
         on the "NoRecipientAction" option.  One of the pos-
         sible actions is to add an "Apparently-To:"  header










Sendmail Installation and Operation Guide          SMM:08-33


         line for any recipients it is aware of.

              The  Apparently-To: header is non-standard and
         is both deprecated and strongly discouraged.

      2.9.3.  Precedence

              The Precedence: header can be used as a  crude
         control  of  message  priority.  It tweaks the sort
         order in the queue and can be configured to  change
         the  message  timeout  values.  The precedence of a
         message also controls how delivery status notifica-
         tions (DSNs) are processed for that message.

   2.10.  IDENT Protocol Support

           Sendmail  supports  the IDENT protocol as defined
      in RFC 1413.  Note that the RFC states a client should
      wait  at least 30 seconds for a response.  The default
      Timeout.ident is 5 seconds as many sites have  adopted
      the practice of dropping IDENT queries.  This has lead
      to delays processing  mail.   Although  this  enhances
      identification  of  the  author of an email message by
      doing a ``call back'' to the originating system to in-
      clude  the owner of a particular TCP connection in the
      audit trail it is in no sense  perfect;  a  determined
      forger  can easily spoof the IDENT protocol.  The fol-
      lowing description is excerpted from RFC 1413:

           6.  Security Considerations

           The information returned by this protocol  is  at
           most  as  trustworthy as the host providing it OR
           the organization operating the host.   For  exam-
           ple,  a PC in an open lab has few if any controls
           on it to prevent a user from having this protocol
           return  any identifier the user wants.  Likewise,
           if the host has been compromised the  information
           returned may be completely erroneous and mislead-
           ing.

           The Identification Protocol is not intended as an
           authorization  or  access  control  protocol.  At
           best, it provides some additional auditing infor-
           mation  with  respect  to  TCP  connections.   At
           worst, it can provide misleading,  incorrect,  or
           maliciously incorrect information.

           The  use of the information returned by this pro-
           tocol for other than auditing  is  strongly  dis-
           couraged.    Specifically,  using  Identification
           Protocol information to make access control deci-
           sions  -  either  as the primary method (i.e., no










SMM:08-34          Sendmail Installation and Operation Guide


           other checks) or as an adjunct to  other  methods
           may  result  in  a weakening of normal host secu-
           rity.

           An Identification server may  reveal  information
           about users, entities, objects or processes which
           might normally be considered private.  An Identi-
           fication server provides service which is a rough
           analog of the CallerID services provided by  some
           phone companies and many of the same privacy con-
           siderations and arguments that apply to the  Cal-
           lerID  service  apply  to Identification.  If you
           wouldn't run a "finger"  server  due  to  privacy
           considerations  you may not want to run this pro-
           tocol.

      In some cases your system may not work  properly  with
      IDENT  support  due to a bug in the TCP/IP implementa-
      tion.  The symptoms will be that for  some  hosts  the
      SMTP connection will be closed almost immediately.  If
      this is true or if you do not want to use  IDENT,  you
      should  set  the IDENT timeout to zero; this will dis-
      able the IDENT protocol.

3.  ARGUMENTS

        The complete list of arguments to  sendmail  is  de-
   scribed  in  detail  in Appendix A.  Some important argu-
   ments are described here.

   3.1.  Queue Interval

           The amount of time between forking a  process  to
      run  through  the queue is defined by the -q flag.  If
      you run with delivery mode set to i or b this  can  be
      relatively  large, since it will only be relevant when
      a host that was down comes back up.  If you run  in  q
      mode  it  should be relatively short, since it defines
      the maximum amount of time that a message may  sit  in
      the queue.  (See also the MinQueueAge option.)

           RFC  1123  section  5.3.1.1  says that this value
      should be at least 30 minutes (although that  probably
      doesn't make sense if you use ``queue-only'' mode).

           Notice:  the meaning of the interval time depends
      on whether normal queue runners  or  persistent  queue
      runners  are used.  For the former, it is the time be-
      tween subsequent starts of a queue run.  For the  lat-
      ter,  it is the time sendmail waits after a persistent
      queue runner has finished its work to start  the  next
      one.  Hence for persistent queue runners this interval
      should  be  very  low,  typically  no  more  than  two










Sendmail Installation and Operation Guide          SMM:08-35


      minutes.

   3.2.  Daemon Mode

           If  you  allow  incoming mail over an IPC connec-
      tion, you should have a daemon running.   This  should
      be  set  by your /etc/rc file using the -bd flag.  The
      -bd flag and the -q flag may be combined in one call:

          /usr/sbin/sendmail -bd -q30m


           An alternative approach  is  to  invoke  sendmail
      from  inetd(8)  (use the -bs -Am flags to ask sendmail
      to speak SMTP on its standard input and output and  to
      run  as MTA).  This works and allows you to wrap send-
      mail in a TCP wrapper program, but may be a bit slower
      since  the configuration file has to be re-read on ev-
      ery message that comes in.  If you do this, you  still
      need to have a sendmail running to flush the queue:

          /usr/sbin/sendmail -q30m


   3.3.  Forcing the Queue

           In  some  cases  you  may find that the queue has
      gotten clogged for some reason.  You can force a queue
      run  using  the -q flag (with no value).  It is enter-
      taining to use the -v flag (verbose) when this is done
      to watch what happens:

          /usr/sbin/sendmail -q -v


           You  can also limit the jobs to those with a par-
      ticular queue identifier, recipient,  sender,  quaran-
      tine  reason,  or  queue  group using one of the queue
      modifiers.  For example, "-qRberkeley"  restricts  the
      queue  run  to  jobs  that  have the string "berkeley"
      somewhere in one of the  recipient  addresses.   Simi-
      larly,   "-qSstring"  limits  the  run  to  particular
      senders, "-qIstring" limits  it  to  particular  queue
      identifiers,  and  "-qQstring" limits it to particular
      quarantined reasons and only operated  on  quarantined
      queue items, and "-qGstring" limits it to a particular
      queue group.  The named queue group will be  run  even
      if it is set to have 0 runners.  You may also place an
      !  before the I or R or S or Q to indicate  that  jobs
      are  limited to not including a particular queue iden-
      tifier, recipient or sender.  For example,  "-q!Rseat-
      tle" limits the queue run to jobs that do not have the
      string "seattle" somewhere in  one  of  the  recipient










SMM:08-36          Sendmail Installation and Operation Guide


      addresses.   Should  you  need  to terminate the queue
      jobs currently active then a SIGTERM to the parent  of
      the process (or processes) will cleanly stop the jobs.

   3.4.  Debugging

           There  are  a  fairly large number of debug flags
      built into sendmail.  Each debug flag has  a  category
      and  a level.  Higher levels increase the level of de-
      bugging activity; in most cases, this means  to  print
      out  more  information.  The convention is that levels
      greater than nine are "absurd," i.e., they  print  out
      so much information that you wouldn't normally want to
      see them except for debugging that particular piece of
      code.

           You should never run a production sendmail server
      in debug mode.  Many of the debug flags will result in
      debug  output  being sent over the SMTP channel unless
      the option -D is used.  This will  confuse  many  mail
      programs.   However,  for  testing purposes, it can be
      useful when sending mail manually via  telnet  to  the
      port you are using while debugging.

           A  debug  category is either an integer, like 42,
      or a name, like ANSI.  You can specify a range of  nu-
      meric  debug  categories  using the syntax 17-42.  You
      can specify a set of named debug  categories  using  a
      glob  pattern like "sm_trace_*".  At present, only "*"
      and "?"  are supported in these glob patterns.

           Debug flags are set using the -d option; the syn-
      tax is:

          debug-flag:        -d debug-list
          debug-list:        debug-option [ , debug-option ]*
          debug-option:      debug-categories [ . debug-level ]
          debug-categories:  integer | integer - integer | category-pattern
          category-pattern:  [a-zA-Z_*?][a-zA-Z0-9_*?]*
          debug-level:       integer

      where spaces are for reading ease only.  For example,

          -d12               Set category 12 to level 1
          -d12.3             Set category 12 to level 3
          -d3-17             Set categories 3 through 17 to level 1
          -d3-17.4           Set categories 3 through 17 to level 4
          -dANSI             Set category ANSI to level 1
          -dsm_trace_*.3     Set all named categories matching sm_trace_* to level 3

      For  a  complete list of the available debug flags you
      will have to look at the code and the TRACEFLAGS  file
      in  the sendmail distribution (they are too dynamic to










Sendmail Installation and Operation Guide          SMM:08-37


      keep this document up to date).  For a list  of  named
      debug categories in the sendmail binary, use

          ident /usr/sbin/sendmail | grep Debug


   3.5.  Changing the Values of Options

           Options can be overridden using the -o or -O com-
      mand line flags.  For example,

          /usr/sbin/sendmail -oT2m

      sets the T (timeout) option to two  minutes  for  this
      run  only;  the  equivalent line using the long option
      name is

          /usr/sbin/sendmail -OTimeout.queuereturn=2m


           Some options have security  implications.   Send-
      mail  allows  you  to  set these, but relinquishes its
      set-user-ID   or   set-group-ID   permissions   there-
      after[12].

   3.6.  Trying a Different Configuration File

           An alternative configuration file can  be  speci-
      fied using the -C flag; for example,

          /usr/sbin/sendmail -Ctest.cf -oQ/tmp/mqueue

      uses the configuration file test.cf instead of the de-
      fault /etc/mail/sendmail.cf.  If the -C  flag  has  no
      value it defaults to sendmail.cf in the current direc-
      tory.

           Sendmail gives up  set-user-ID  root  permissions
      (if  it  has been installed set-user-ID root) when you
      use this flag, so it  is  common  to  use  a  publicly
      writable  directory (such as /tmp) as the queue direc-
      tory (QueueDirectory or Q option) while testing.




____________________
   [12]That  is,  it sets its effective uid to the real uid;
thus, if you are executing as root, as from  root's  crontab
file  or  during  system  startup  the root permissions will
still be honored.












SMM:08-38          Sendmail Installation and Operation Guide


   3.7.  Logging Traffic

           Many SMTP implementations do not fully  implement
      the  protocol.   For  example,  some personal computer
      based SMTPs do not understand  continuation  lines  in
      reply codes.  These can be very hard to trace.  If you
      suspect such a problem, you can  set  traffic  logging
      using the -X flag.  For example,

          /usr/sbin/sendmail -X /tmp/traffic -bd

      will log all traffic in the file /tmp/traffic.

           This  logs  a lot of data very quickly and should
      NEVER be used during normal operations.  After  start-
      ing  up such a daemon, force the errant implementation
      to send a message to your host.  All  message  traffic
      in  and  out  of sendmail, including the incoming SMTP
      traffic, will be logged in this file.

   3.8.  Testing Configuration Files

           When you build a configuration table, you can  do
      a  certain  amount of testing using the "test mode" of
      sendmail.  For example, you could invoke sendmail as:

          sendmail -bt -Ctest.cf

      which would read the configuration file "test.cf"  and
      enter test mode.  In this mode, you enter lines of the
      form:

          rwset address

      where rwset is the rewriting set you want to  use  and
      address  is an address to apply the set to.  Test mode
      shows you the steps it takes as it  proceeds,  finally
      showing  you the address it ends up with.  You may use
      a comma separated list of rwsets for sequential appli-
      cation of rules to an input.  For example:

          3,1,21,4 monet:bollard

      first  applies  ruleset three to the input "monet:bol-
      lard."  Ruleset one is then applied to the  output  of
      ruleset  three, followed similarly by rulesets twenty-
      one and four.

           If you need more detail, you  can  also  use  the
      "-d21" flag to turn on more debugging.  For example,

          sendmail -bt -d21.99











Sendmail Installation and Operation Guide          SMM:08-39


      turns on an incredible amount of information; a single
      word address is probably going to  print  out  several
      pages worth of information.

           You  should  be  warned that internally, sendmail
      applies ruleset 3 to all addresses.  In test mode  you
      will  have  to  do  that manually.  For example, older
      versions allowed you to use

          0 bruce@broadcast.sony.com

      This version requires that you use:

          3,0 bruce@broadcast.sony.com


           As of version 8.7, some other syntaxes are avail-
      able in test mode:

      .Dxvalue  defines macro x to have the indicated value.
                This is useful when debugging rules that use
                the $&x syntax.

      .Ccvalue  adds the indicated value to class c.

      =Sruleset dumps the contents of the indicated ruleset.

      -ddebug-spec
                is equivalent to the command-line flag.

      Version 8.9 introduced more features:

      ?         shows a help message.

      =M        display the known mailers.

      $m        print the value of macro m.

      $=c       print the contents of class c.

      /mx host  returns the MX records for `host'.

      /parse address
                parse address, returning the value of crack-
                addr, and the parsed address.

      /try mailer addr
                rewrite address into the form it  will  have
                when presented to the indicated mailer.

      /tryflags flags
                set flags used by parsing.  The flags can be
                `H' for Header or `E' for Envelope, and  `S'










SMM:08-40          Sendmail Installation and Operation Guide


                for  Sender or `R' for Recipient.  These can
                be combined, `HR' sets flags for header  re-
                cipients.

      /canon hostname
                try to canonify hostname.

      /map mapname key
                look up `key' in the indicated `mapname'.

      /quit     quit address test mode.

   3.9.  Persistent Host Status Information

           When  HostStatusDirectory is enabled, information
      about the status of hosts is maintained  on  disk  and
      can thus be shared between different instantiations of
      sendmail.  The status of the last connection with each
      remote host may be viewed with the command:

          sendmail -bh

      This information may be flushed with the command:

          sendmail -bH

      Flushing  the  information  prevents new sendmail pro-
      cesses from loading it, but does not prevent  existing
      processes  from using the status information that they
      already have.

4.  TUNING

        There are a number of configuration  parameters  you
   may want to change, depending on the requirements of your
   site.  Most of these are set using an option in the  con-
   figuration   file.    For  example,  the  line  "O  Time-
   out.queuereturn=5d" sets option "Timeout.queuereturn"  to
   the value "5d" (five days).

        Most  of these options have appropriate defaults for
   most sites.  However, sites having very high  mail  loads
   may  find they need to tune them as appropriate for their
   mail load.  In particular,  sites  experiencing  a  large
   number  of small messages, many of which are delivered to
   many recipients, may find that they need  to  adjust  the
   parameters dealing with queue priorities.

        All  versions  of  sendmail  prior to 8.7 had single
   character option names.  As of  8.7,  options  have  long
   (multi-character  names).   Although  old short names are
   still accepted, most new options do not have short equiv-
   alents.










Sendmail Installation and Operation Guide          SMM:08-41


        This section only describes the options you are most
   likely to want to tweak; read section 5 for more details.

   4.1.  Timeouts

           All time intervals are set using a scaled syntax.
      For  example,  "10m"  represents  ten minutes, whereas
      "2h30m" represents two and a half hours.  The full set
      of scales is:

          s   seconds
          m   minutes
          h   hours
          d   days
          w   weeks


      4.1.1.  Queue interval

              The  argument to the -q flag specifies how of-
         ten a sub-daemon will run the queue.  This is typi-
         cally  set to between fifteen minutes and one hour.
         If not set, or set to zero, the queue will  not  be
         run automatically.  RFC 1123 section 5.3.1.1 recom-
         mends that this be at least 30 minutes.  Should you
         need  to  terminate the queue jobs currently active
         then a SIGTERM to the parent  of  the  process  (or
         processes) will cleanly stop the jobs.

      4.1.2.  Read timeouts

              Timeouts all have option names "Timeout.subop-
         tion".  Most of these control SMTP operations.  The
         recognized  suboptions,  their  default values, and
         the minimum values  allowed  by  RFC  2821  section
         4.5.3.2 (or RFC 1123 section 5.3.2) are:

         connect   The  time  to wait for an SMTP connection
                   to open (the connect(2) system call)  [0,
                   unspecified].   If  zero, uses the kernel
                   default.  In no case can this option  ex-
                   tend  the  timeout longer than the kernel
                   provides, but it can shorten it.  This is
                   to get around kernels that provide an ab-
                   surdly long connection timeout  (90  min-
                   utes in one case).

         iconnect  The  same  as  connect, except it applies
                   only to the initial attempt to connect to
                   a  host  for a given message [0, unspeci-
                   fied].  The concept is that  this  should
                   be very short (a few seconds); hosts that
                   are well connected  and  responsive  will










SMM:08-42          Sendmail Installation and Operation Guide


                   thus be serviced immediately.  Hosts that
                   are slow will not hold up other  deliver-
                   ies in the initial delivery attempt.

         aconnect  [0,   unspecified]  The  overall  timeout
                   waiting for all connection for  a  single
                   delivery  attempt  to  succeed.  If 0, no
                   overall limit is applied.   This  can  be
                   used to restrict the total amount of time
                   trying to connect to a long list of  host
                   that  could  accept an e-mail for the re-
                   cipient.  This timeout does not apply  to
                   FallbackMXhost,  i.e., if the time is ex-
                   hausted,  the  FallbackMXhost  is   tried
                   next.

         initial   The  wait  for  the  initial 220 greeting
                   message [5m, 5m].

         helo      The wait for a reply from a HELO or  EHLO
                   command  [5m, unspecified].  This may re-
                   quire a host name lookup, so five minutes
                   is probably a reasonable minimum.

         mail*     The  wait for a reply from a MAIL command
                   [10m, 5m].

         rcpt*     The wait for a reply from a RCPT  command
                   [1h, 5m].  This should be long because it
                   could be pointing at a list that takes  a
                   long time to expand (see below).

         datainit* The  wait for a reply from a DATA command
                   [5m, 2m].

         datablock*#
                   The wait for reading a data  block  (that
                   is,  the body of the message).  [1h, 3m].
                   This should be long because it  also  ap-
                   plies  to  programs piping input to send-
                   mail which have no guarantee  of  prompt-
                   ness.

         datafinal*
                   The  wait for a reply from the dot termi-
                   nating a message.  [1h, 10m].  If this is
                   shorter than the time actually needed for
                   the receiver to deliver the message,  du-
                   plicates will be generated.  This is dis-
                   cussed in RFC 1047.

         rset      The wait for a reply from a RSET  command
                   [5m, unspecified].










Sendmail Installation and Operation Guide          SMM:08-43


         quit      The  wait for a reply from a QUIT command
                   [2m, unspecified].

         misc      The wait for a reply  from  miscellaneous
                   (but short) commands such as NOOP (no-op-
                   eration) and VERB (go into verbose mode).
                   [2m, unspecified].

         command*# In  server SMTP, the time to wait for an-
                   other command.  [1h, 5m].

         ident#    The timeout waiting for  a  reply  to  an
                   IDENT query [5s[13], unspecified].

         lhlo      The wait for a reply to an LMTP LHLO com-
                   mand [2m, unspecified].

         auth      The  timeout  for a reply in an SMTP AUTH
                   dialogue [10m, unspecified].

         starttls  The timeout for a reply to an SMTP START-
                   TLS  command  and  the TLS handshake [1h,
                   unspecified].

         fileopen# The timeout for opening .forward and :in-
                   clude: files [60s, none].

         control#  The timeout for a complete control socket
                   transaction to complete [2m, none].

         hoststatus#
                   How long status information about a  host
                   (e.g.,  host  down) will be cached before
                   it is  considered  stale  [30m,  unspeci-
                   fied].

         resolver.retrans#
                   The resolver's retransmission time inter-
                   val (in  seconds)  [varies].   Sets  both
                   Timeout.resolver.retrans.first  and Time-
                   out.resolver.retrans.normal.

         resolver.retrans.first#
                   The resolver's retransmission time inter-
                   val (in seconds) for the first attempt to
                   deliver a message [varies].


____________________
   [13]On  some systems the default is zero to turn the pro-
tocol off entirely.












SMM:08-44          Sendmail Installation and Operation Guide


         resolver.retrans.normal#
                   The resolver's retransmission time inter-
                   val (in seconds) for all resolver lookups
                   except   the   first   delivery   attempt
                   [varies].

         resolver.retry#
                   The  number  of times to retransmit a re-
                   solver  query.   Sets  both   Timeout.re-
                   solver.retry.first     and    Timeout.re-
                   solver.retry.normal [varies].

         resolver.retry.first#
                   The number of times to retransmit  a  re-
                   solver query for the first attempt to de-
                   liver a message [varies].

         resolver.retry.normal#
                   The number of times to retransmit  a  re-
                   solver query for all resolver lookups
                    except   the   first   delivery  attempt
                   [varies].

         For compatibility with old configuration files,  if
         no  suboption is specified, all the timeouts marked
         with an asterick  (*)  are  set  to  the  indicated
         value.   All but those marked with a pound sign (#)
         apply to client SMTP.

              For example, the lines:

             O Timeout.command=25m
             O Timeout.datablock=3h

         sets the server SMTP command timeout to 25  minutes
         and the input data block timeout to three hours.

      4.1.3.  Message timeouts

              After  sitting in the queue for a few days, an
         undeliverable message will time out.   This  is  to
         insure that at least the sender is aware of the in-
         ability to send a message.  The  timeout  is  typi-
         cally set to five days.  It is sometimes considered
         convenient to also send a warning  message  if  the
         message  is  in  the  queue longer than a few hours
         (assuming you normally have good  connectivity;  if
         your  messages  normally took several hours to send
         you wouldn't want to do this because it wouldn't be
         an  unusual  event).   These timeouts are set using
         the Timeout.queuereturn and  Timeout.queuewarn  op-
         tions  in  the  configuration file (previously both
         were set using the T option).










Sendmail Installation and Operation Guide          SMM:08-45


              If the message is submitted using  the  NOTIFY
         SMTP  extension, warning messages will only be sent
         if NOTIFY=DELAY is specified.  The queuereturn  and
         queuewarn  timeouts can be further qualified with a
         tag based on the Precedence: field in the  message;
         they must be one of "urgent" (indicating a positive
         non-zero precedence), "normal" (indicating  a  zero
         precedence),  or  "non-urgent" (indicating negative
         precedences).  For example, setting "Timeout.queue-
         warn.urgent=1h" sets the warning timeout for urgent
         messages only to  one  hour.   The  default  if  no
         precedence  is  indicated is to set the timeout for
         all precedences.  If the message has a normal  (de-
         fault) precedence and it is a delivery status noti-
         fication (DSN), Timeout.queuereturn.dsn  and  Time-
         out.queuewarn.dsn  can  be used to give an alterna-
         tive warn and return  time  for  DSNs.   The  value
         "now" can be used for -O Timeout.queuereturn to re-
         turn entries immediately during a queue run,  e.g.,
         to bounce messages independent of their time in the
         queue.

              Since these options are global, and since  you
         cannot  know a priori how long another host outside
         your domain will be down, a  five  day  timeout  is
         recommended.   This  allows  a recipient to fix the
         problem even if it occurs at  the  beginning  of  a
         long  weekend.   RFC 1123 section 5.3.1.1 says that
         this parameter should be ``at least 4-5 days''.

              The Timeout.queuewarn value can be piggybacked
         on  the T option by indicating a time after which a
         warning message should be sent;  the  two  timeouts
         are separated by a slash.  For example, the line

             OT5d/4h

         causes email to fail after five days, but a warning
         message will be sent after four hours.  This should
         be  large  enough  that  the message will have been
         tried several times.

   4.2.  Forking During Queue Runs

           By setting the ForkEachJob (Y)  option,  sendmail
      will fork before each individual message while running
      the queue.  This option was used with earlier releases
      to  prevent  sendmail  from consuming large amounts of
      memory.  It should no longer be necessary  with  send-
      mail  8.12.   If  the  ForkEachJob  option is not set,
      sendmail will keep track of hosts that are down during
      a  queue  run,  which can improve performance dramati-
      cally.










SMM:08-46          Sendmail Installation and Operation Guide


           If the ForkEachJob option is set, sendmail cannot
      use connection caching.

   4.3.  Queue Priorities

           Every  message  is assigned a priority when it is
      first instantiated, consisting of the message size (in
      bytes)  offset  by  the message class (which is deter-
      mined from the Precedence:  header)  times  the  "work
      class  factor"  and the number of recipients times the
      "work recipient factor."  The priority is used to  or-
      der  the  queue.  Higher numbers for the priority mean
      that the message will be processed later when  running
      the queue.

           The  message  size is included so that large mes-
      sages are penalized relative to small  messages.   The
      message  class  allows  users  to send "high priority"
      messages by including a "Precedence:" field  in  their
      message; the value of this field is looked up in the P
      lines of the configuration file.  Since the number  of
      recipients  affects  the  amount  of  load  a  message
      presents to the system, this is also included into the
      priority.

           The recipient and class factors can be set in the
      configuration file using the RecipientFactor  (y)  and
      ClassFactor (z) options respectively.  They default to
      30000 (for the recipient factor)  and  1800  (for  the
      class factor).  The initial priority is:

     pri=msgsize-(classxClassFactor)+(nrcptxRecipientFactor)

      (Remember,  higher  values for this parameter actually
      mean that the job will be treated  with  lower  prior-
      ity.)

           The  priority  of a job can also be adjusted each
      time it is processed (that is, each time an attempt is
      made  to deliver it) using the "work time factor," set
      by the RetryFactor (Z) option.  This is added  to  the
      priority,  so  it normally decreases the precedence of
      the job, on the grounds that  jobs  that  have  failed
      many times will tend to fail again in the future.  The
      RetryFactor option defaults to 90000.

   4.4.  Load Limiting

           Sendmail can be asked to queue (but not  deliver)
      mail  if  the  system load average gets too high using
      the QueueLA (x) option.  When the load average exceeds
      the  value of the QueueLA option, the delivery mode is
      set to q (queue only) if the  QueueFactor  (q)  option










Sendmail Installation and Operation Guide          SMM:08-47


      divided  by the difference in the current load average
      and the QueueLA option plus one is less than the  pri-
      ority of the message -- that is, the message is queued
      iff:

                        pri>LQueueFactor_

      The QueueFactor option defaults  to  600000,  so  each
      point  of load average is worth 600000 priority points
      (as described above).

           For drastic cases, the RefuseLA  (X)  option  de-
      fines  a load average at which sendmail will refuse to
      accept network connections.  Locally  generated  mail,
      i.e.,  mail which is not submitted via SMTP (including
      incoming UUCP mail), is still accepted.   Notice  that
      the  MSP  submits  mail to the MTA via SMTP, and hence
      mail will be queued in the  client  queue  in  such  a
      case.   Therefore  it  is  necessary to run the client
      mail queue periodically.

   4.5.  Resource Limits

           Sendmail has several parameters  to  control  re-
      source  usage.  Besides those mentionted in the previ-
      ous section, there  are  at  least  MaxDaemonChildren,
      ConnectionRateThrottle,  MaxQueueChildren, and MaxRun-
      nersPerQueue.  The latter  two  limit  the  number  of
      sendmail  processes  that operate on the queue.  These
      are discussed in the section  ``Queue  Group  Declara-
      tion''.   The former two can be used to limit the num-
      ber of incoming connections.  Their appropriate values
      depend  on the host operating system and the hardware,
      e.g., amount of memory.  In many situations  it  might
      be  useful  to  set limits to prevent to have too many
      sendmail  processes,  however,  these  limits  can  be
      abused to mount a denial of service attack.  For exam-
      ple, if MaxDaemonChildren=10 then an attacker needs to
      open  only  10 SMTP sessions to the server, leave them
      idle for most of the time,  and  no  more  connections
      will  be  accepted.   If  this  option is set then the
      timeouts used in a SMTP session should be lowered from
      their default values to their minimum values as speci-
      fied in RFC 2821 and listed in section 4.1.2.

   4.6.  Measures against Denial of Service Attacks

           Sendmail has some built-in measures against  sim-
      ple  denial of service (DoS) attacks.  The SMTP server
      by default slows down if too many bad commands are is-
      sued or if some commands are repeated too often within
      a session.  Details can be found in  the  source  file
      sendmail/srvrsmtp.c   by   looking   for   the   macro










SMM:08-48          Sendmail Installation and Operation Guide


      definitions of MAXBADCOMMANDS, MAXNOOPCOMMANDS, MAXHE-
      LOCOMMANDS,  MAXVRFYCOMMANDS, and MAXETRNCOMMANDS.  If
      an SMTP command is issued more often than  the  corre-
      sponding  MAXcmdCOMMANDS  value,  then the response is
      delayed exponentially, starting with a sleep  time  of
      one  second,  up  to a maximum of four minutes (as de-
      fined by MAXTIMEOUT).  If the option MaxDaemonChildren
      is  set  to a value greater than zero, then this could
      make a DoS attack even worse since it keeps a  connec-
      tion  open longer than necessary.  Therefore a connec-
      tion is terminated with a 421 SMTP reply code  if  the
      number  of  commands  exceeds the limit by a factor of
      two and MAXBADCOMMANDS is set to a value greater  than
      zero (the default is 25).

   4.7.  Delivery Mode

           There  are  a number of delivery modes that send-
      mail can operate in, set by the DeliveryMode (d)  con-
      figuration  option.   These  modes specify how quickly
      mail will be delivered.  Legal modes are:

          i   deliver interactively (synchronously)
          b   deliver in background (asynchronously)
          q   queue only (don't deliver)
          d   defer delivery attempts (don't deliver)

      There are tradeoffs.  Mode "i" gives  the  sender  the
      quickest  feedback, but may slow down some mailers and
      is hardly ever necessary.  Mode "b" delivers  promptly
      but can cause large numbers of processes if you have a
      mailer that takes a long time to  deliver  a  message.
      Mode "q" minimizes the load on your machine, but means
      that delivery may be delayed for up to the  queue  in-
      terval.  Mode "d" is identical to mode "q" except that
      it also prevents lookups in maps including the -D flag
      from working during the initial queue phase; it is in-
      tended for ``dial on demand'' sites where DNS  lookups
      might  cost  real  money.   Some simple error messages
      (e.g., host unknown during the SMTP protocol) will  be
      delayed  using  this  mode.  Mode "b" is the usual de-
      fault.

           If you run in mode "q" (queue only), "d" (defer),
      or  "b"  (deliver in background) sendmail will not ex-
      pand aliases and follow .forward  files  upon  initial
      receipt  of  the mail.  This speeds up the response to
      RCPT commands.  Mode "i" should not  be  used  by  the
      SMTP server.














Sendmail Installation and Operation Guide          SMM:08-49


   4.8.  Log Level

           The  level  of  logging  can be set for sendmail.
      The default using a standard  configuration  table  is
      level 9.  The levels are as follows:

      0    Minimal logging.

      1    Serious  system  failures  and potential security
           problems.

      2    Lost communications (network problems) and proto-
           col failures.

      3    Other   serious  failures,  malformed  addresses,
           transient  forward/include   errors,   connection
           timeouts.

      4    Minor failures, out of date alias databases, con-
           nection rejections via check_ rulesets.

      5    Message collection statistics.

      6    Creation of error messages, VRFY  and  EXPN  com-
           mands.

      7    Delivery failures (host or user unknown, etc.).

      8    Successful  deliveries  and  alias  database  re-
           builds.

      9    Messages being deferred  (due  to  a  host  being
           down, etc.).

      10   Database  expansion  (alias,  forward, and userdb
           lookups) and authentication information.

      11   NIS errors and end of job processing.

      12   Logs all SMTP connections.

      13   Log bad user shells, files with improper  permis-
           sions, and other questionable situations.

      14   Logs refused connections.

      15   Log all incoming and outgoing SMTP commands.

      20   Logs  attempts  to run locked queue files.  These
           are not errors, but can be useful to note if your
           queue appears to be clogged.












SMM:08-50          Sendmail Installation and Operation Guide


      30   Lost  locks  (only  if  using  lockf  instead  of
           flock).

      Additionally, values above 64  are  reserved  for  ex-
      tremely  verbose  debugging  output.   No  normal site
      would ever set these.

   4.9.  File Modes

           The modes used for files depend on what function-
      ality  you want and the level of security you require.
      In many cases sendmail does careful  checking  of  the
      modes  of  files  and  directories to avoid accidental
      compromise; if you want to make it  possible  to  have
      group-writable  support  files you may need to use the
      DontBlameSendmail option to turn  off  some  of  these
      checks.

      4.9.1.  To suid or not to suid?

              Sendmail is no longer installed set-user-ID to
         root.  sendmail/SECURITY explains how to  configure
         and  install  sendmail  without set-user-ID to root
         but set-group-ID which is the default configuration
         starting with 8.12.

              The  daemon usually runs as root, unless other
         measures are taken.  At the point where sendmail is
         about  to exec(2) a mailer, it checks to see if the
         userid is zero (root); if so, it resets the  userid
         and  groupid  to a default (set by the U= equate in
         the mailer line; if that is not set,  the  Default-
         User  option  is  used).  This can be overridden by
         setting the S flag to the mailer for  mailers  that
         are  trusted  and must be called as root.  However,
         this will cause mail  processing  to  be  accounted
         (using sa(8)) to root rather than to the user send-
         ing the mail.

              A middle ground is to set  the  RunAsUser  op-
         tion.  This causes sendmail to become the indicated
         user as soon as it has done the  startup  that  re-
         quires root privileges (primarily, opening the SMTP
         socket).  If you use RunAsUser, the queue directory
         (normally  /var/spool/mqueue)  should  be  owned by
         that user, and all files and  databases  (including
         user  .forward files, alias files, :include: files,
         and external databases) must be  readable  by  that
         user.   Also,  since  sendmail  will not be able to
         change its uid, delivery to programs or files  will
         be  marked as unsafe, e.g., undeliverable, in .for-
         ward, aliases, and :include: files.  Administrators
         can  override this by setting the DontBlameSendmail










Sendmail Installation and Operation Guide          SMM:08-51


         option to the setting  NonRootSafeAddr.   RunAsUser
         is probably best suited for firewall configurations
         that don't have regular user logins.  If the option
         is  used on a system which performs local delivery,
         then the local delivery agent must have the  proper
         permissions  (i.e., usually set-user-ID root) since
         it will be invoked by the RunAsUser, not by root.

      4.9.2.  Turning off security checks

              Sendmail is very particular about the modes of
         files that it reads or writes.  For example, by de-
         fault it will refuse to read most  files  that  are
         group  writable on the grounds that they might have
         been tampered with by someone other than the owner;
         it will even refuse to read files in group writable
         directories.  Also, sendmail will refuse to  create
         a new aliases database in an unsafe directory.  You
         can get around this by manually creating the  data-
         base  file as a trusted user ahead of time and then
         rebuilding the aliases database with newaliases.

              If you are quite sure that your  configuration
         is  safe and you want sendmail to avoid these secu-
         rity checks, you can turn off certain checks  using
         the  DontBlameSendmail  option.   This option takes
         one or more names that disable checks.  In the  de-
         scriptions  that follow, "unsafe directory" means a
         directory that is writable by anyone other than the
         owner.  The values are:

         Safe No special handling.

         AssumeSafeChown
              Assume  that  the  chown  system  call  is re-
              stricted to root.  Since some versions of UNIX
              permit  regular users to give away their files
              to other users on some  filesystems,  sendmail
              often cannot assume that a given file was cre-
              ated by the owner, particularly when it is  in
              a  writable  directory.  You can set this flag
              if you know that file giveaway  is  restricted
              on your system.

         ClassFileInUnsafeDirPath
              When  reading class files (using the F line in
              the configuration file), allow files that  are
              in unsafe directories.

         DontWarnForwardFileInUnsafeDirPath
              Prevent logging of unsafe directory path warn-
              ings for non-existent forward files.











SMM:08-52          Sendmail Installation and Operation Guide


         ErrorHeaderInUnsafeDirPath
              Allow the file named in the ErrorHeader option
              to be in an unsafe directory.

         FileDeliveryToHardLink
              Allow delivery to files that are hard links.

         FileDeliveryToSymLink
              Allow  delivery  to  files  that  are symbolic
              links.

         ForwardFileInGroupWritableDirPath
              Allow .forward files in group writable  direc-
              tories.

         ForwardFileInUnsafeDirPath
              Allow .forward files in unsafe directories.

         ForwardFileInUnsafeDirPathSafe
              Allow a .forward file that is in an unsafe di-
              rectory to include references to  program  and
              files.

         GroupReadableKeyFile
              Accept a group-readable key file for STARTTLS.

         GroupReadableSASLDBFile
              Accept  a  group-readable  Cyrus SASL password
              file.

         GroupReadableDefaultAuthInfoFile
              Accept a group-readable  DefaultAuthInfo  file
              for SASL.

         GroupWritableAliasFile
              Allow group-writable alias files.

         GroupWritableDirPathSafe
              Change the definition of "unsafe directory" to
              consider  group-writable  directories  to   be
              safe.   World-writable  directories are always
              unsafe.

         GroupWritableForwardFile
              Allow group writable .forward files.

         GroupWritableForwardFileSafe
              Accept group-writable .forward files  as  safe
              for program and file delivery.

         GroupWritableIncludeFile
              Allow group wriable :include: files.











Sendmail Installation and Operation Guide          SMM:08-53


         GroupWritableIncludeFileSafe
              Accept  group-writable :include: files as safe
              for program and file delivery.

         GroupWritableSASLDBFile
              Accept a group-writable  Cyrus  SASL  password
              file.

         HelpFileInUnsafeDirPath
              Allow the file named in the HelpFile option to
              be in an unsafe directory.

         IncludeFileInGroupWritableDirPath
              Allow :include: files in group writable direc-
              tories.

         IncludeFileInUnsafeDirPath
              Allow :include: files in unsafe directories.

         IncludeFileInUnsafeDirPathSafe
              Allow  a  :include:  file that is in an unsafe
              directory to include references to program and
              files.

         InsufficientEntropy
              Try  to  use  STARTTLS  even  if  the PRNG for
              OpenSSL is not properly seeded despite the se-
              curity problems.

         LinkedAliasFileInWritableDir
              Allow  an  alias  file  that  is  a  link in a
              writable directory.

         LinkedClassFileInWritableDir
              Allow class files that are links  in  writable
              directories.

         LinkedForwardFileInWritableDir
              Allow   .forward   files  that  are  links  in
              writable directories.

         LinkedIncludeFileInWritableDir
              Allow  :include:  files  that  are  links   in
              writable directories.

         LinkedMapInWritableDir
              Allow map files that are links in writable di-
              rectories.   This  includes   alias   database
              files.

         LinkedServiceSwitchFileInWritableDir
              Allow  the  service  switch  file to be a link
              even if the directory is writable.










SMM:08-54          Sendmail Installation and Operation Guide


         MapInUnsafeDirPath
              Allow maps (e.g., hash, btree, and dbm  files)
              in  unsafe  directories.   This includes alias
              database files.

         NonRootSafeAddr
              Do not mark file and program deliveries as un-
              safe  if  sendmail  is  not  running with root
              privileges.

         RunProgramInUnsafeDirPath
              Run programs that are in writable  directories
              without logging a warning.

         RunWritableProgram
              Run programs that are group- or world-writable
              without logging a warning.

         TrustStickyBit
              Allow group or world writable  directories  if
              the  sticky  bit  is set on the directory.  Do
              not set this on systems which do not honor the
              sticky bit on directories.

         WorldWritableAliasFile
              Accept world-writable alias files.

         WorldWritableForwardfile
              Allow world writable .forward files.

         WorldWritableIncludefile
              Allow world wriable :include: files.

         WriteMapToHardLink
              Allow writes to maps that are hard links.

         WriteMapToSymLink
              Allow writes to maps that are symbolic links.

         WriteStatsToHardLink
              Allow the status file to be a hard link.

         WriteStatsToSymLink
              Allow the status file to be a symbolic link.

   4.10.  Connection Caching

           When  processing  the queue, sendmail will try to
      keep the last  few  open  connections  open  to  avoid
      startup  and shutdown costs.  This only applies to IPC
      and LPC connections.












Sendmail Installation and Operation Guide          SMM:08-55


           When trying to open a  connection  the  cache  is
      first searched.  If an open connection is found, it is
      probed to see if it is still active by sending a  RSET
      command.   It  is not an error if this fails; instead,
      the connection is closed and reopened.

           Two parameters control the connection cache.  The
      ConnectionCacheSize  (k)  option defines the number of
      simultaneous open connections that will be  permitted.
      If  it  is  set to zero, connections will be closed as
      quickly as possible.  The default is one.  This should
      be  set  as  appropriate for your system size; it will
      limit the amount of  system  resources  that  sendmail
      will  use  during  queue  runs.  Never set this higher
      than 4.

           The ConnectionCacheTimeout (K)  option  specifies
      the  maximum  time  that any cached connection will be
      permitted to idle.  When the idle  time  exceeds  this
      value the connection is closed.  This number should be
      small (under ten minutes) to prevent you from grabbing
      too  many  resources from other hosts.  The default is
      five minutes.

   4.11.  Name Server Access

           Control of host address lookups  is  set  by  the
      hosts  service  entry in your service switch file.  If
      you are on a system that has built-in  service  switch
      support  (e.g.,  Ultrix,  Solaris,  or DEC OSF/1) then
      your system is probably configured  properly  already.
      Otherwise,    sendmail    will    consult   the   file
      /etc/mail/service.switch,  which  should  be  created.
      Sendmail only uses two entries: hosts and aliases, al-
      though system routines may use other services (notably
      the  passwd  service  for  user name lookups by getpw-
      name).

           However, some systems (such as SunOS 4.X) will do
      DNS  lookups  regardless of the setting of the service
      switch entry.  In particular, the system routine geth-
      ostbyname(3)  is  used to look up host names, and many
      vendor versions try some combination of DNS, NIS,  and
      file lookup in /etc/hosts without consulting a service
      switch.  Sendmail makes no attempt to work around this
      problem,  and  the DNS lookup will be done anyway.  If
      you do not have a nameserver configured at  all,  such
      as  at  a UUCP-only site, sendmail will get a "connec-
      tion refused" message when it tries to connect to  the
      name  server.   If the hosts switch entry has the ser-
      vice "dns" listed somewhere in the list, sendmail will
      interpret  this  to  mean a temporary failure and will
      queue the mail for  later  processing;  otherwise,  it










SMM:08-56          Sendmail Installation and Operation Guide


      ignores the name server data.

           The  same  technique is used to decide whether to
      do MX lookups.  If you want MX support, you must  have
      "dns" listed as a service in the hosts switch entry.

           The  ResolverOptions  (I)  option  allows  you to
      tweak name server options.  The command line  takes  a
      series of flags as documented in resolver(3) (with the
      leading "RES_" deleted).  Each can be preceded  by  an
      optional `+' or `-'.  For example, the line

          O ResolverOptions=+AAONLY -DNSRCH

      turns  on  the  AAONLY  (accept  authoritative answers
      only) and turns off  the  DNSRCH  (search  the  domain
      path)   options.    Most  resolver  libraries  default
      DNSRCH, DEFNAMES, and RECURSE flags on and all  others
      off.   If  NETINET6 is enabled, most libraries default
      to USE_INET6 as well.  You can also include  "HasWild-
      cardMX"  to specify that there is a wildcard MX record
      matching your domain; this turns off MX matching  when
      canonifying  names,  which  can  lead to inappropriate
      canonifications.   Use   "WorkAroundBrokenAAAA"   when
      faced  with  a broken nameserver that returns SERVFAIL
      (a temporary failure) on T_AAAA (IPv6) lookups  during
      hostname  canonification.   Notice: it might be neces-
      sary to apply the same (or similar)  options  to  sub-
      mit.cf too.

           Version  level  1 configurations (see the section
      about ``Configuration Version Level'') turn DNSRCH and
      DEFNAMES  off  when  doing delivery lookups, but leave
      them on everywhere else.  Version 8  of  sendmail  ig-
      nores them when doing canonification lookups (that is,
      when using $[ ... $]), and always does the search.  If
      you  don't  want to do automatic name extension, don't
      call $[ ... $].

           The search rules for $[ ... $] are somewhat  dif-
      ferent than usual.  If the name being looked up has at
      least one dot, it always  tries  the  unmodified  name
      first.   If  that  fails,  it tries the reduced search
      path, and lastly tries the unmodified name  (but  only
      for  names  without a dot, since names with a dot have
      already  been  tried).   This  allows  names  such  as
      ``utc.CS''  to match the site in Czechoslovakia rather
      than the site in your local Computer  Science  depart-
      ment.   It  also  prefers  A and CNAME records over MX
      records -- that is, if it finds an MX record it  makes
      note  of it, but keeps looking.  This way, if you have
      a wildcard MX record matching your domain, it will not
      assume that all names match.










Sendmail Installation and Operation Guide          SMM:08-57


           To  completely turn off all name server access on
      systems without service switch support (such as  SunOS
      4.X)  you  will  have to recompile with -DNAMED_BIND=0
      and remove -lresolv from the list of libraries  to  be
      searched when linking.

   4.12.  Moving the Per-User Forward Files

           Some  sites mount each user's home directory from
      a local disk on their workstation, so that  local  ac-
      cess  is  fast.   However, the result is that .forward
      file lookups from a central mail server are slow.   In
      some cases, mail can even be delivered on machines in-
      appropriately because of a  file  server  being  down.
      The  performance  can be especially bad if you run the
      automounter.

           The ForwardPath (J) option allows you  to  set  a
      path  of  forward files.  For example, the config file
      line

          O ForwardPath=/var/forward/$u:$z/.forward.$w

      would first look for a file with the same name as  the
      user's login in /var/forward; if that is not found (or
      is inaccessible) the file ``.forward.machinename''  in
      the  user's  home directory is searched.  A truly per-
      verse site could also search by sender  by  using  $r,
      $s, or $f.

           If  you  create a directory such as /var/forward,
      it should be mode 1777 (that is, the sticky bit should
      be  set).   Users  should  create the files mode 0644.
      Note that you must use the  ForwardFileInUnsafeDirPath
      and   ForwardFileInUnsafeDirPathSafe  flags  with  the
      DontBlameSendmail option to allow forward files  in  a
      world  writable directory.  This might also be used as
      a denial of service attack (users could create forward
      files  for other users); a better approach might be to
      create /var/forward mode 0755 and create  empty  files
      for  each user, owned by that user, mode 0644.  If you
      do this, you don't have to set  the  DontBlameSendmail
      options indicated above.

   4.13.  Free Space

           On  systems  that have one of the system calls in
      the statfs(2) family (including  statvfs  and  ustat),
      you can specify a minimum number of free blocks on the
      queue filesystem using the MinFreeBlocks  (b)  option.
      If there are fewer than the indicated number of blocks
      free on the filesystem on which the queue  is  mounted
      the  SMTP  server  will reject mail with the 452 error










SMM:08-58          Sendmail Installation and Operation Guide


      code.  This invites  the  SMTP  client  to  try  again
      later.

           Beware  of  setting  this option too high; it can
      cause rejection of email when that mail would be  pro-
      cessed without difficulty.

   4.14.  Maximum Message Size

           To  avoid  overflowing  your  system with a large
      message, the MaxMessageSize option can be set  to  set
      an  absolute  limit  on  the  size of any one message.
      This will be advertised  in  the  ESMTP  dialogue  and
      checked during message collection.

   4.15.  Privacy Flags

           The  PrivacyOptions  (p) option allows you to set
      certain ``privacy'' flags.   Actually,  many  of  them
      don't  give you any extra privacy, rather just insist-
      ing that client SMTP servers use the HELO command  be-
      fore using certain commands or adding extra headers to
      indicate possible spoof attempts.

           The option takes a series of flag names; the  fi-
      nal  privacy  is the inclusive or of those flags.  For
      example:

          O PrivacyOptions=needmailhelo, noexpn

      insists that the HELO or EHLO command be used before a
      MAIL  command  is  accepted and disables the EXPN com-
      mand.

           The flags are detailed in section 5.6.

   4.16.  Send to Me Too

           Beginning with version 8.10, sendmail includes by
      default  the (envelope) sender in any list expansions.
      For example, if "matt" sends to a list  that  contains
      "matt" as one of the members he will get a copy of the
      message.  If the MeToo option is set to FALSE (in  the
      configuration  file or via the command line), this be-
      havior is changed, i.e., the (envelope) sender is  ex-
      cluded in list expansions.

5.  THE WHOLE SCOOP ON THE CONFIGURATION FILE

        This section describes the configuration file in de-
   tail.












Sendmail Installation and Operation Guide          SMM:08-59


        There is one point that should be made clear immedi-
   ately:  the  syntax of the configuration file is designed
   to be reasonably easy to parse, since this is done  every
   time  sendmail starts up, rather than easy for a human to
   read or write.  The configuration file should  be  gener-
   ated via the method described in cf/README, it should not
   be edited directly unless someone is  familiar  with  the
   internals of the syntax described here and it is not pos-
   sible to achieve  the  desired  result  via  the  default
   method.

        The  configuration  file is organized as a series of
   lines, each of  which  begins  with  a  single  character
   defining  the  semantics for the rest of the line.  Lines
   beginning with a space or a tab  are  continuation  lines
   (although  the  semantics  are  not  well defined in many
   places).  Blank lines and lines beginning  with  a  sharp
   symbol (`#') are comments.

   5.1.  R and S -- Rewriting Rules

           The  core  of  address  parsing are the rewriting
      rules.  These are an ordered production system.  Send-
      mail  scans through the set of rewriting rules looking
      for a match on the left hand side (LHS) of  the  rule.
      When  a  rule  matches, the address is replaced by the
      right hand side (RHS) of the rule.

           There are several sets of rewriting rules.   Some
      of  the  rewriting  sets  are used internally and must
      have specific semantics.  Other rewriting sets do  not
      have  specifically assigned semantics, and may be ref-
      erenced by the mailer definitions or by other  rewrit-
      ing sets.

           The syntax of these two commands are:

          Sn

      Sets the current ruleset being collected to n.  If you
      begin a ruleset more than once it appends to  the  old
      definition.

          Rlhs rhs comments

      The fields must be separated by at least one tab char-
      acter; there may be embedded  spaces  in  the  fields.
      The lhs is a pattern that is applied to the input.  If
      it matches, the input is rewritten to  the  rhs.   The
      comments are ignored.

           Macro  expansions  of  the  form $x are performed
      when the configuration file is read.  A literal $  can










SMM:08-60          Sendmail Installation and Operation Guide


      be  included using $$.  Expansions of the form $&x are
      performed at run time using a  somewhat  less  general
      algorithm.   This is intended only for referencing in-
      ternally defined macros such as $h that are changed at
      runtime.

      5.1.1.  The left hand side

              The left hand side of rewriting rules contains
         a pattern.  Normal words  are  simply  matched  di-
         rectly.   Metasyntax  is  introduced using a dollar
         sign.  The metasymbols are:

             $*   Match zero or more tokens
             $+   Match one or more tokens
             $-   Match exactly one token
             $=x  Match any phrase in class x
             $~x  Match any word not in class x

         If any of these match, they  are  assigned  to  the
         symbol  $n  for replacement on the right hand side,
         where n is the index in the LHS.  For  example,  if
         the LHS:

             $-:$+

         is applied to the input:

             UCBARPA:eric

         the  rule  will match, and the values passed to the
         RHS will be:

             $1  UCBARPA
             $2  eric


              Additionally, the LHS can include $@ to  match
         zero tokens.  This is not bound to a $n on the RHS,
         and is normally only used when it stands  alone  in
         order to match the null input.

      5.1.2.  The right hand side

              When  the  left  hand side of a rewriting rule
         matches, the input is deleted and replaced  by  the
         right  hand  side.  Tokens are copied directly from
         the RHS unless  they  begin  with  a  dollar  sign.
         Metasymbols are:














Sendmail Installation and Operation Guide          SMM:08-61


             $n         Substitute indefinite token n from LHS
             $[name$]   Canonicalize name
             $(map key $@arguments $:default $)
                        Generalized keyed mapping function
             $>n        "Call" ruleset n
             $#mailer   Resolve to mailer
             $@host     Specify host
             $:user     Specify user


              The  $n  syntax  substitutes the corresponding
         value from a $+, $-, $*, $=, or  $~  match  on  the
         LHS.  It may be used anywhere.

              A  host  name  enclosed  between  $[ and $] is
         looked up in the host database(s) and  replaced  by
         the canonical  name[14].   For  example,  "$[ftp$]"
         might      become     "ftp.CS.Berkeley.EDU"     and
         "$[[128.32.130.2]$]"     would     become     "van-
         gogh.CS.Berkeley.EDU."  Sendmail recognizes its nu-
         meric IP address without calling  the  name  server
         and replaces it with its canonical name.

              The  $(  ...  $) syntax is a more general form
         of lookup; it uses a named map instead  of  an  im-
         plicit  map.   If no lookup is found, the indicated
         default is inserted; if no default is specified and
         no  lookup  matches,  the  value is left unchanged.
         The arguments are passed to the  map  for  possible
         use.

              The  $>n  syntax  causes  the remainder of the
         line to be substituted as usual and then passed  as
         the  argument  to  ruleset  n.   The final value of
         ruleset n then becomes the  substitution  for  this
         rule.   The  $> syntax expands everything after the
         ruleset name to the end of the  replacement  string
         and  then  passes  that as the initial input to the
         ruleset.  Recursive calls are allowed.   For  exam-
         ple,

             $>0 $>3 $1

         expands  $1,  passes  that  to  ruleset 3, and then
         passes the result of ruleset 3 to ruleset 0.

              The $# syntax should only be used  in  ruleset
         zero,  a  subroutine  of  ruleset zero, or rulesets
____________________
   [14]This  is  actually  completely  equivalent  to $(host
hostname$).  In particular, a $: default can be used.












SMM:08-62          Sendmail Installation and Operation Guide


         that  return  decisions  (e.g.,  check_rcpt).    It
         causes evaluation of the ruleset to terminate imme-
         diately, and signals to sendmail that  the  address
         has  completely  resolved.  The complete syntax for
         ruleset 0 is:

             $#mailer $@host $:user

         This specifies the  {mailer,  host,  user}  3-tuple
         necessary  to  direct  the mailer.  Note: the third
         element ( user ) is often also called address part.
         If  the  mailer is local the host part may be omit-
         ted[15].  The mailer must be a single word, but the
         host and user may be multi-part.  If the mailer  is
         the  built-in  IPC mailer, the host may be a colon-
         separated list of hosts that are searched in  order
         for  the  first  working  address  (exactly like MX
         records).  The  user  is  later  rewritten  by  the
         mailer-specific envelope rewriting set and assigned
         to the $u macro.  As a special case, if the  mailer
         specified  has the F=@ flag specified and the first
         character of the  $:  value  is  "@",  the  "@"  is
         stripped  off, and a flag is set in the address de-
         scriptor that causes sendmail to not do  ruleset  5
         processing.

              Normally, a rule that matches is retried, that
         is, the rule loops until it fails.  A RHS may  also
         be  preceded  by a $@ or a $: to change this behav-
         ior.  A $@ prefix causes the ruleset to return with
         the remainder of the RHS as the value.  A $: prefix
         causes the rule to terminate immediately,  but  the
         ruleset to continue; this can be used to avoid con-
         tinued  application  of  a  rule.   The  prefix  is
         stripped before continuing.

              The  $@ and $: prefixes may precede a $> spec;
         for example:

             R$+     $: $>7 $1

         matches anything, passes that to ruleset seven, and
         continues; the $: is necessary to avoid an infinite
         loop.


____________________
   [15]You may want to use it for special "per user"  exten-
sions.   For  example, in the address "jgm+foo@CMU.EDU"; the
"+foo" part is not part of the user name, and is  passed  to
the local mailer for local use.












Sendmail Installation and Operation Guide          SMM:08-63


              Substitution occurs in  the  order  described,
         that  is,  parameters from the LHS are substituted,
         hostnames  are  canonicalized,  "subroutines"   are
         called, and finally $#, $@, and $: are processed.

      5.1.3.  Semantics of rewriting rule sets

              There  are  six  rewriting sets that have spe-
         cific semantics.  Five of these are related as  de-
         picted by figure 1.

              Ruleset  three  should  turn  the address into
         "canonical form."  This form should have the  basic
         syntax:

             local-part@host-domain-spec

         Ruleset  three  is applied by sendmail before doing
         anything with any address.

              If no "@" sign is specified, then the host-do-
         main-spec  may  be  appended  (box "D" in Figure 1)
         from the sender address (if the C flag  is  set  in
         the  mailer definition corresponding to the sending
         mailer).

              Ruleset zero is applied after ruleset three to
         addresses that are going to actually specify recip-
         ients.  It must resolve to  a  {mailer,  host,  ad-
         dress}  triple.   The mailer must be defined in the

____________________________________________________________

                    +---+
                 -->| 0 |-->resolved address
                /   +---+
               /            +---+   +---+
              /        ---->| 1 |-->| S |--
       +---+ / +---+  /     +---+   +---+  \    +---+
addr-->| 3 |-->| D |--                      --->| 4 |-->msg
       +---+   +---+  \     +---+   +---+  /    +---+
                        --->| 2 |-->| R |--
                            +---+   +---+

            Figure 1 -- Rewriting set semantics
          D -- sender domain addition
          S -- mailer-specific sender rewriting
          R -- mailer-specific recipient rewriting
____________________________________________________________














SMM:08-64          Sendmail Installation and Operation Guide


         mailer definitions  from  the  configuration  file.
         The  host  is  defined into the $h macro for use in
         the argv expansion of the  specified  mailer.   No-
         tice:  since  the  envelope  sender address will be
         used if a  delivery  status  notification  must  be
         send,  i.e., is may specify a recipient, it is also
         run through ruleset zero.  If ruleset zero  returns
         a  temporary  error  4xy then delivery is deferred.
         This can be used to temporarily  disable  delivery,
         e.g., based on the time of the day or other varying
         parameters.  It should not be used to quarantine e-
         mails.

              Rulesets one and two are applied to all sender
         and recipient addresses respectively.  They are ap-
         plied  before any specification in the mailer defi-
         nition.  They must never resolve.

              Ruleset four is applied to  all  addresses  in
         the message.  It is typically used to translate in-
         ternal to external form.

              In addition, ruleset 5 is applied to all local
         addresses  (specifically,  those  that resolve to a
         mailer with the `F=5' flag set) that  do  not  have
         aliases.   This allows a last minute hook for local
         names.

      5.1.4.  Ruleset hooks

              A few extra rulesets are  defined  as  "hooks"
         that  can be defined to get special features.  They
         are all named rulesets.  The  "check_*"  forms  all
         give  accept/reject  status; falling off the end or
         returning normally is an accept, and  resolving  to
         $#error is a reject or quarantine.  Quarantining is
         chosen by specifying quarantine in the second  part
         of the mailer triplet:

             $#error $@ quarantine $: Reason for quarantine

         Many  of  these  can  also  resolve  to the special
         mailer name $#discard; this accepts the message  as
         though  it  were  successful  but  then discards it
         without delivery.  Note, this mailer cannot be cho-
         sen  as  a mailer in ruleset 0.  Note also that all
         "check_*" rulesets  have  to  deal  with  temporary
         failures,  especially  for map lookups, themselves,
         i.e., they should return a temporary error code  or
         at  least  they  should  make  a proper decision in
         those cases.












Sendmail Installation and Operation Guide          SMM:08-65


         5.1.4.1.  check_relay

                 The check_relay ruleset is called  after  a
            connection is accepted by the daemon.  It is not
            called when sendmail is started  using  the  -bs
            option.  It is passed

                client.host.name $| client.host.address

            where  $|  is a metacharacter separating the two
            parts.  This ruleset can reject connections from
            various locations.  Note that it only checks the
            connecting SMTP client IP address and  hostname.
            It does not check for third party message relay-
            ing.  The  check_rcpt  ruleset  discussed  below
            usually does third party message relay checking.

         5.1.4.2.  check_mail

                 The  check_mail  ruleset is passed the user
            name parameter of the SMTP MAIL command.  It can
            accept or reject the address.

         5.1.4.3.  check_rcpt

                 The  check_rcpt  ruleset is passed the user
            name parameter of the SMTP RCPT command.  It can
            accept or reject the address.

         5.1.4.4.  check_data

                 The  check_data ruleset is called after the
            SMTP DATA command, its parameter is  the  number
            of recipients.  It can accept or reject the com-
            mand.

         5.1.4.5.  check_compat

                 The check_compat ruleset is passed

                sender-address $| recipient-address

            where $| is a metacharacter separating  the  ad-
            dresses.   It can accept or reject mail transfer
            between these two addresses much like the check-
            compat()  function.   Note:  while other check_*
            rulesets are invoked during the  SMTP  mail  re-
            ceiption  stage  (i.e.,  in  the  SMTP  server),
            check_compat is invoked during the mail delivery
            stage.













SMM:08-66          Sendmail Installation and Operation Guide


         5.1.4.6.  check_eoh

                 The check_eoh ruleset is passed

                number-of-headers $| size-of-headers

            where  $| is a metacharacter separating the num-
            bers.  These numbers can be used for  size  com-
            parisons  with  the  arith  map.  The ruleset is
            triggered after all of  the  headers  have  been
            read.   It  can be used to correlate information
            gathered from  those  headers  using  the  macro
            storage map.  One possible use is to check for a
            missing header.  For example:

                Kstorage macro
                HMessage-Id: $>CheckMessageId

                SCheckMessageId
                # Record the presence of the header
                R$*            $: $(storage {MessageIdCheck} $@ OK $) $1
                R< $+ @ $+ >   $@ OK
                R$*            $#error $: 553 Header Error

                Scheck_eoh
                # Check the macro
                R$*            $: < $&{MessageIdCheck} >
                # Clear the macro for the next message
                R$*            $: $(storage {MessageIdCheck} $) $1
                # Has a Message-Id: header
                R< $+ >        $@ OK
                # Allow missing Message-Id: from local mail
                R$*            $: < $&{client_name} >
                R< >           $@ OK
                R< $=w >       $@ OK
                # Otherwise, reject the mail
                R$*            $#error $: 553 Header Error

            Keep in mind the Message-Id: header is not a re-
            quired header and is not a guaranteed spam indi-
            cator.  This ruleset is an  example  and  should
            probably not be used in production.

         5.1.4.7.  check_eom

                 The  check_eom  ruleset is called after the
            end of a message, its parameter is  the  message
            size.  It can accept or reject the message.

         5.1.4.8.  check_etrn

                 The check_etrn ruleset is passed the param-
            eter of the SMTP ETRN command.  It can accept or










Sendmail Installation and Operation Guide          SMM:08-67


            reject the command.

         5.1.4.9.  check_expn

                 The  check_expn  ruleset is passed the user
            name parameter of the SMTP EXPN command.  It can
            accept or reject the address.

         5.1.4.10.  check_vrfy

                 The  check_vrfy  ruleset is passed the user
            name parameter of the SMTP VRFY command.  It can
            accept or reject the command.

         5.1.4.11.  trust_auth

                 The  trust_auth ruleset is passed the AUTH=
            parameter of the SMTP MAIL command.  It is  used
            to   determine  whether  this  value  should  be
            trusted. In order to  make  this  decision,  the
            ruleset  may  make  use of the various ${auth_*}
            macros.  If the ruleset does resolve to the "er-
            ror"  mailer  the AUTH= parameter is not trusted
            and hence not passed on to the next relay.

         5.1.4.12.  tls_client

                 The tls_client ruleset is called when send-
            mail  acts  as  server, after a STARTTLS command
            has been issued, and from check_mail.   The  pa-
            rameter  is  the value of ${verify} and STARTTLS
            or MAIL, respectively.  If the ruleset does  re-
            solve to the "error" mailer, the appropriate er-
            ror code is returned to the client.

         5.1.4.13.  tls_server

                 The tls_server ruleset is called when send-
            mail  acts  as  client  after a STARTTLS command
            (should) have been issued.  The parameter is the
            value of ${verify}.  If the ruleset does resolve
            to the "error" mailer, the connection is aborted
            (treated  as non-deliverable with a permanent or
            temporary error).

         5.1.4.14.  tls_rcpt

                 The tls_rcpt ruleset is  called  each  time
            before a RCPT TO command is sent.  The parameter
            is the current recipient.  If the  ruleset  does
            resolve  to the "error" mailer, the RCPT TO com-
            mand is suppressed (treated  as  non-deliverable
            with  a  permanent  or  temporary  error).  This










SMM:08-68          Sendmail Installation and Operation Guide


            ruleset allows to require encryption or  verifi-
            cation  of  the recipient's MTA even if the mail
            is somehow redirected to another host.  For  ex-
            ample,  sending mail to luke@endmail.org may get
            redirected to a host named death.star and  hence
            the  tls_server  ruleset won't apply.  By intro-
            ducing per recipient restrictions  such  attacks
            (e.g., via DNS spoofing) can be made impossible.
            See cf/README how this ruleset can be used.

         5.1.4.15.  srv_features

                 The srv_features ruleset is called with the
            connecting client's host name when a client con-
            nects to sendmail.  This ruleset  should  return
            $# followed by a list of options (single charac-
            ters delimited by white space).  If  the  return
            value  starts  with anything else it is silently
            ignored.  Generally upper case  characters  turn
            off  a  feature while lower case characters turn
            it on.  Option `S' causes the server not to  of-
            fer  STARTTLS,  which is useful to interact with
            MTAs/MUAs that have broken STARTTLS  implementa-
            tions  by simply not offering it.  `V' turns off
            the request for a client certificate during  the
            TLS  handshake.   Options  `A'  and `P' suppress
            SMTP AUTH and PIPELINING, respectively.  `c'  is
            the   equivalent   to  AuthOptions=p,  i.e.,  it
            doesn't permit mechanisms susceptible to  simple
            passive  attack  (e.g.,  PLAIN, LOGIN), unless a
            security layer is active.  Option  `l'  requires
            SMTP  AUTH  for a connection.  Options 'B', 'D',
            'E', and 'X' suppress SMTP VERB, DSN, ETRN,  and
            EXPN, respectively.





























Sendmail Installation and Operation Guide          SMM:08-69


                A        Do not offer AUTH
                a        Offer AUTH (default)
                B        Do not offer VERB
                b        Offer VERB (default)
                C        Do not require security layer for
                         plaintext AUTH (default)
                c        Require security layer for plaintext AUTH
                D        Do not offer DSN
                d        Offer DSN (default)
                E        Do not offer ETRN
                e        Offer ETRN (default)
                L        Do not require AUTH (default)
                l        Require AUTH
                P        Do not offer PIPELINING
                p        Offer PIPELINING (default)
                S        Do not offer STARTTLS
                s        Offer STARTTLS (default)
                V        Do not request a client certificate
                v        Request a client certificate (default)
                X        Do not offer EXPN
                x        Offer EXPN (default)

            Note:  the  entries  marked as ``(default)'' may
            require that some configuration has  been  made,
            e.g.,  SMTP  AUTH  is only available if properly
            configured.   Moreover,  many  options  can   be
            changed  on a global basis via other settings as
            explained in this document, e.g., via DaemonPor-
            tOptions.

                 The ruleset may return `$#temp' to indicate
            that there is a  temporary  problem  determining
            the correct features, e.g., if a map is unavail-
            able.  In that case, the SMTP  server  issues  a
            temporary failure and does not accept email.

         5.1.4.16.  try_tls

                 The try_tls ruleset is called when sendmail
            connects to another MTA.  If  the  ruleset  does
            resolve to the "error" mailer, sendmail does not
            try STARTTLS even if it  is  offered.   This  is
            useful  to  deal  with STARTTLS interoperability
            issues by simply not using it.

         5.1.4.17.  tls_srv_features and tls_clt_features

                 The tls_clt_features ruleset is called when
            sendmail   connects   to  another  MTA  and  the
            tls_srv_features ruleset is called when a client
            connects  to  sendmail.   The  arguments for the
            rulesets are the host name and IP address of the
            other   side   separated   by  $|  (which  is  a










SMM:08-70          Sendmail Installation and Operation Guide


            metacharacter).  They should return  a  list  of
            key=value  pairs  separated  by  semicolons; the
            list can be empty if no options  should  be  ap-
            plied to the connection.  Available keys are and
            their allowed values are:

            Options
              A comma separated list of SSL related options.
              See  ServerSSLOptions and ClientSSLOptions for
              details, as  well  as  SSL_set_options(3)  and
              note  this warning: Options already set before
              are not cleared!

            CipherList
              Specify cipher  list  for  STARTTLS,  see  ci-
              phers(1)  for possible values.  This overrides
              the global CipherList for the session.

            CertFile
              File containing a certificate.

            KeyFile
              File containing the private key for  the  cer-
              tificate.

            Example:

                Stls_srv_features
                R$* $| 10.$+   $: cipherlist=HIGH


            Notes:

                 Errors  in  these  features  (e.g., unknown
            keys or invalid values) are logged and the  cur-
            rent  session is aborted to avoid using STARTTLS
            with features that should have been changed.

                 The keys are case-insensitive.

                 Both CertFile and KeyFile must be specified
            together; specifying only one is an error.

                 These  rulesets require the sendmail binary
            to be built with _FFR_TLS_SE_OPTS  enabled  (see
            the "For Future Release" section).

         5.1.4.18.  authinfo

                 The  authinfo  ruleset is called when send-
            mail tries to authenticate to another  MTA.   It
            should  return  $#  followed by a list of tokens
            that are used for  SMTP  AUTH.   If  the  return










Sendmail Installation and Operation Guide          SMM:08-71


            value  starts  with anything else it is silently
            ignored.  Each token is a tagged string  of  the
            form: "TDstring" (including the quotes), where

                T        Tag which describes the item
                D        Delimiter: ':' simple text follows
                         '=' string is base64 encoded
                string   Value of the item

            Valid values for the tag are:

                U        user (authorization) id
                I        authentication id
                P        password
                R        realm
                M        list of mechanisms delimited by spaces

            If  this ruleset is defined, the option Default-
            AuthInfo is ignored (even if  the  ruleset  does
            not return a ``useful'' result).

         5.1.4.19.  queuegroup

                 The queuegroup ruleset is used to map a re-
            cipient address to a queue group name.  The  in-
            put  for  the  ruleset is a recipient address as
            specified by the SMTP RCPT command.  The ruleset
            should return $# followed by the name of a queue
            group.  If the return value starts with anything
            else  it  is  silently ignored.  See the section
            about ``Queue Groups and Queue Directories'' for
            further information.

         5.1.4.20.  greet_pause

                 The  greet_pause ruleset is used to specify
            the amount of time to pause before  sending  the
            initial  SMTP  220  greeting.  If any traffic is
            received during that pause, an SMTP  554  rejec-
            tion response is given instead of the 220 greet-
            ing and all SMTP commands  are  rejected  during
            that  connection.  This helps protect sites from
            open proxies and  SMTP  slammers.   The  ruleset
            should  return $# followed by the number of mil-
            liseconds (thousandths of a  second)  to  pause.
            If the return value starts with anything else or
            is not a number, it is silently ignored.   Note:
            this  ruleset is not invoked (and hence the fea-
            ture is disabled) when the smtps (SMTP over SSL)
            is  used,  i.e.,  the  s modifier is set for the
            daemon via DaemonPortOptions,  because  in  this
            case  the  SSL handshake is performed before the
            greeting is sent.










SMM:08-72          Sendmail Installation and Operation Guide


      5.1.5.  IPC mailers

              Some special processing occurs if the  ruleset
         zero  resolves  to an IPC mailer (that is, a mailer
         that has "[IPC]" listed as the Path in the  M  con-
         figuration  line.   The host name passed after "$@"
         has MX expansion performed if not delivering via  a
         named socket; this looks the name up in DNS to find
         alternate delivery sites.

              The host name can also be provided as a dotted
         quad or an IPv6 address in square brackets; for ex-
         ample:

             [128.32.149.78]

         or

             [IPv6:2002:c0a8:51d2::23f4]

         This causes direct conversion of the numeric  value
         to an IP host address.

              The  host  name  passed  in after the "$@" may
         also be a colon-separated list of hosts.   Each  is
         separately MX expanded and the results are concate-
         nated to make (essentially) one long MX list.   The
         intent here is to create "fake" MX records that are
         not published in DNS for private internal networks.

              As a final special case, the host name can  be
         passed in as a text string in square brackets:

             [ucbvax.berkeley.edu]

         This form avoids the MX mapping.  N.B.: This is in-
         tended only for situations where you have a network
         firewall  or  other  host that will do special pro-
         cessing for all your mail, so that your  MX  record
         points  to  a  gateway  machine; this machine could
         then do direct delivery to machines within your lo-
         cal  domain.  Use of this feature directly violates
         RFC 1123 section  5.3.5:  it  should  not  be  used
         lightly.

   5.2.  D -- Define Macro

           Macros  are named with a single character or with
      a word in {braces}.  The names ``x'' and  ``{x}''  de-
      note  the same macro for every single character ``x''.
      Single character names may be selected from the entire
      ASCII  set, but user-defined macros should be selected
      from the set of upper case letters only.   Lower  case










Sendmail Installation and Operation Guide          SMM:08-73


      letters and special symbols are used internally.  Long
      names beginning with a lower case letter or a punctua-
      tion  character  are  reserved for use by sendmail, so
      user-defined long macro names should begin with an up-
      per case letter.

           The syntax for macro definitions is:

          Dxval

      where  x is the name of the macro (which may be a sin-
      gle character or a word in  braces)  and  val  is  the
      value it should have.  There should be no spaces given
      that do not actually belong in the macro value.

           Macros are interpolated using the  construct  $x,
      where  x  is the name of the macro to be interpolated.
      This interpolation is done when the configuration file
      is read, except in M lines.  The special construct $&x
      can be used in R lines to get deferred interpolation.

           Conditionals can be specified using the syntax:

          $?x text1 $| text2 $.

      This interpolates text1 if the macro  $x  is  set  and
      non-null, and text2 otherwise.  The "else" ($|) clause
      may be omitted.

           The following macros are defined and/or used  in-
      ternally by sendmail for interpolation into argv's for
      mailers or for other contexts.  The ones marked *  are
      information  passed into sendmail[16], the ones marked
      # are information passed both in and out of  sendmail,
      and the unmarked macros are passed out of sendmail but
      are not otherwise used internally.  These macros are:

      $a   The origination date in RFC 822 format.  This  is
           extracted from the Date: line.

      $b   The current date in RFC 822 format.

      $c   The  hop count.  This is a count of the number of
           Received: lines plus the value of the -h  command
           line flag.


____________________
   [16]As  of  version 8.6, all of these macros have reason-
able defaults.  Previous versions required that they be  de-
fined.












SMM:08-74          Sendmail Installation and Operation Guide


      $d   The current date in UNIX (ctime) format.

      $e*  (Obsolete;  use  SmtpGreetingMessage  option  in-
           stead.)  The SMTP entry message.  This is printed
           out  when SMTP starts up.  The first word must be
           the $j macro as specified by RFC  821.   Defaults
           to  "$j Sendmail $v ready at $b".  Commonly rede-
           fined to include the configuration  version  num-
           ber, e.g., "$j Sendmail $v/$Z ready at $b"

      $f   The envelope sender (from) address.

      $g   The  sender  address  relative  to the recipient.
           For  example,  if  $f  is  "foo",  $g   will   be
           "host!foo", "foo@host.domain", or whatever is ap-
           propriate for the receiving mailer.

      $h   The recipient host.  This is  set  in  ruleset  0
           from the $@ field of a parsed address.

      $i   The queue id, e.g., "f344MXxp018717".

      $j#  The  "official"  domain name for this site.  This
           is fully qualified if the full qualification  can
           be  found.   It must be redefined to be the fully
           qualified domain name if your system is not  con-
           figured so that information can find it automati-
           cally.

      $k   The UUCP node name (from the uname system call).

      $l*  (Obsolete; use UnixFromLine option instead.)  The
           format  of  the  UNIX from line.  Unless you have
           changed the UNIX mailbox format, you  should  not
           change the default, which is "From $g $d".

      $m   The  domain part of the gethostname return value.
           Under normal circumstances, $j is  equivalent  to
           $w.$m.

      $n*  The name of the daemon (for error messages).  De-
           faults to "MAILER-DAEMON".

      $o*  (Obsolete:  use  OperatorChars  option  instead.)
           The  set  of "operators" in addresses.  A list of
           characters which will be  considered  tokens  and
           which  will  separate  tokens when doing parsing.
           For example, if "@" were in the  $o  macro,  then
           the input "a@b" would be scanned as three tokens:
           "a," "@," and "b."  Defaults to ".:@[]", which is
           the  minimum set necessary to do RFC 822 parsing;
           a richer set of operators  is  ".:%@!/[]",  which
           adds  support  for  UUCP,  the  %-hack, and X.400










Sendmail Installation and Operation Guide          SMM:08-75


           addresses.

      $p   Sendmail's process id.

      $q*  Default format of sender address.  The  $q  macro
           specifies  how an address should appear in a mes-
           sage when it is defaulted.  Defaults  to  "<$g>".
           It is commonly redefined to be "$?x$x <$g>$|$g$."
           or "$g$?x ($x)$.", corresponding to the following
           two formats:

               Eric Allman <eric@CS.Berkeley.EDU>
               eric@CS.Berkeley.EDU (Eric Allman)

           Sendmail  properly quotes names that have special
           characters if the first form is used.

      $r   Protocol used to receive the message.   Set  from
           the  -p  command  line flag or by the SMTP server
           code.

      $s   Sender's host name.  Set from the -p command line
           flag or by the SMTP server code (in which case it
           is set to the EHLO/HELO parameter).

      $t   A numeric representation of the current  time  in
           the  format YYYYMMDDHHmm (4 digit year 1900-9999,
           2 digit month 01-12, 2 digit day 01-31,  2  digit
           hours 00-23, 2 digit minutes 00-59).

      $u   The recipient user.

      $v   The version number of the sendmail binary.

      $w#  The hostname of this site.  This is the root name
           of this host (but see below for caveats).

      $x   The full name of the sender.

      $z   The home directory of the recipient.

      $_   The   validated   sender   address.    See   also
           ${client_resolve}.

      ${addr_type}
           The  type of the address which is currently being
           rewritten.  This macro contains up to three char-
           acters,  the first is either `e' or `h' for enve-
           lope/header address, the second is a  space,  and
           the third is either `s' or `r' for sender/recipi-
           ent address.












SMM:08-76          Sendmail Installation and Operation Guide


      ${alg_bits}
           The maximum keylength (in bits) of the  symmetric
           encryption  algorithm  used for a TLS connection.
           This may be less than  the  effective  keylength,
           which  is  stored in ${cipher_bits}, for ``export
           controlled'' algorithms.

      ${auth_authen}
           The client's authentication credentials as deter-
           mined by authentication (only set if successful).
           The format depends  on  the  mechanism  used,  it
           might  be  just `user', or `user@realm', or some-
           thing similar (SMTP AUTH only).

      ${auth_author}
           The authorization identity, i.e. the AUTH= param-
           eter of the SMTP MAIL command if supplied.

      ${auth_type}
           The  mechanism used for SMTP authentication (only
           set if successful).

      ${auth_ssf}
           The keylength (in bits) of the symmetric  encryp-
           tion  algorithm  used for the security layer of a
           SASL mechanism.

      ${bodytype}
           The message body type (7BIT or 8BITMIME), as  de-
           termined from the envelope.

      ${cert_fp}
           The  fingerprint  of  the  presented  certificate
           (STARTTLS only).  Note: this macro  is  only  de-
           fined  if  the option CertFingerprintAlgorithm is
           set, in which case the specified fingerprint  al-
           gorithm  is used.  The valid algorithms depend on
           the OpenSSL version, but usually md5,  sha1,  and
           sha256 are available.  See

               openssl dgst -h

           for a list.

      ${cert_issuer}
           The  DN  (distinguished name) of the CA (certifi-
           cate authority) that signed  the  presented  cer-
           tificate (the cert issuer) (STARTTLS only).

      ${cert_md5}
           The MD5 hash of the presented certificate (START-
           TLS only).  Note: this macro is only  defined  if
           the option CertFingerprintAlgorithm is not set.










Sendmail Installation and Operation Guide          SMM:08-77


      ${cert_subject}
           The  DN  of the presented certificate (called the
           cert subject) (STARTTLS only).

      ${cipher}
           The cipher suite used for the  connection,  e.g.,
           EDH-DSS-DES-CBC3-SHA,  EDH-RSA-DES-CBC-SHA,  DES-
           CBC-MD5, DES-CBC3-SHA (STARTTLS only).

      ${cipher_bits}
           The effective keylength (in bits) of the  symmet-
           ric  encryption  algorithm used for a TLS connec-
           tion.

      ${client_addr}
           The IP address of  the  SMTP  client.   IPv6  ad-
           dresses  are  tagged  with "IPv6:" before the ad-
           dress.  Defined in the SMTP server only.

      ${client_connections}
           The number of open connections in the SMTP server
           for the client IP address.

      ${client_flags}
           The  flags  specified  by  the  Modifier= part of
           ClientPortOptions where flags are separated  from
           each  other  by  spaces  and upper case flags are
           doubled.  That is,  Modifier=hA  will  be  repre-
           sented as "h AA" in ${client_flags}, which is re-
           quired for testing the flags in rulesets.

      ${client_name}
           The host name of the SMTP client.   This  may  be
           the  client's  bracketed IP address in the form [
           nnn.nnn.nnn.nnn    ]    for    IPv4     and     [
           IPv6:nnnn:...:nnnn  ] for IPv6 if the client's IP
           address is not resolvable, or if it is resolvable
           but  the  IP  address  of  the  resolved hostname
           doesn't match the original IP  address.   Defined
           in  the  SMTP server only.  See also ${client_re-
           solve}.

      ${client_port}
           The port number of the SMTP client.   Defined  in
           the SMTP server only.

      ${client_ptr}
           The  result  of  the PTR lookup for the client IP
           address.    Note:   this   is   the    same    as
           ${client_name}  if  and only if ${client_resolve}
           is OK.  Defined in the SMTP server only.












SMM:08-78          Sendmail Installation and Operation Guide


      ${client_rate}
           The number of incoming connections for the client
           IP  address  over  the time interval specified by
           ConnectionRateWindowSize.

      ${client_resolve}
           Holds  the  result  of  the  resolve   call   for
           ${client_name}.  Possible values are:

               OK        resolved successfully
               FAIL      permanent lookup failure
               FORGED    forward lookup doesn't match reverse lookup
               TEMP      temporary lookup failure

           Defined  in  the SMTP server only.  sendmail per-
           forms a hostname lookup on the IP address of  the
           connecting client.  Next the IP addresses of that
           hostname are looked up.  If the client IP address
           does  not  appear in that list, then the hostname
           is maybe forged.  This is reflected as the  value
           FORGED for ${client_resolve} and it also shows up
           in $_ as "(may be forged)".

      ${cn_issuer}
           The CN (common name) of the CA  that  signed  the
           presented  certificate (STARTTLS only).  Note: if
           the CN cannot be extracted properly  it  will  be
           replaced by one of these strings based on the en-
           countered error:

               BadCertificateContainsNULCN contains a NUL character
               BadCertificateTooLong    CN is too long
               BadCertificateUnknown    CN could not be extracted

           In the last case, some other  (unspecific)  error
           occurred.

      ${cn_subject}
           The CN (common name) of the presented certificate
           (STARTTLS only).  See ${cn_issuer}  for  possible
           replacements.

      ${currHeader}
           Header value as quoted string (possibly truncated
           to MAXNAME).  This macro  is  only  available  in
           header check rulesets.

      ${daemon_addr}
           The  IP  address  the  daemon is listening on for
           connections.

      ${daemon_family}
           The network family if  the  daemon  is  accepting










Sendmail Installation and Operation Guide          SMM:08-79


           network  connections.   Possible  values  include
           "inet", "inet6", "iso", "ns", "x.25"

      ${daemon_flags}
           The flags for the daemon as specified by the Mod-
           ifier=  part  of  DaemonPortOptions  whereby  the
           flags are separated from each  other  by  spaces,
           and upper case flags are doubled.  That is, Modi-
           fier=Ea will be represented as "EE a"  in  ${dae-
           mon_flags},  which  is  required  for testing the
           flags in rulesets.

      ${daemon_info}
           Some information about a daemon as a text string.
           For example, "SMTP+queueing@00:30:00".

      ${daemon_name}
           The  name  of  the  daemon from DaemonPortOptions
           Name= suboption.  If this suboption is  not  set,
           "Daemon#", where # is the daemon number, is used.

      ${daemon_port}
           The  port  the daemon is accepting connection on.
           Unless DaemonPortOptions is set, this  will  most
           likely be "25".

      ${deliveryMode}
           The  current delivery mode sendmail is using.  It
           is initially set to the value of the DeliveryMode
           option.

      ${envid}
           The  envelope  id  parameter  (ENVID=)  passed to
           sendmail as part of the envelope.

      ${hdrlen}
           The length of the header value which is stored in
           ${currHeader}  (before  possible truncation).  If
           this value is greater than or  equal  to  MAXNAME
           the header has been truncated.

      ${hdr_name}
           The  name  of the header field for which the cur-
           rent header check ruleset has been called.   This
           is  useful  for a default header check ruleset to
           get the name of the header;  the  macro  is  only
           available in header check rulesets.

      ${if_addr}
           The  IP  address  of the interface of an incoming
           connection unless it  is  in  the  loopback  net.
           IPv6 addresses are tagged with "IPv6:" before the
           address.










SMM:08-80          Sendmail Installation and Operation Guide


      ${if_addr_out}
           The IP address of the interface  of  an  outgoing
           connection  unless  it  is  in  the loopback net.
           IPv6 addresses are tagged with "IPv6:" before the
           address.

      ${if_family}
           The  IP  family  of  the interface of an incoming
           connection unless it is in the loopback net.

      ${if_family_out}
           The IP family of the  interface  of  an  outgoing
           connection unless it is in the loopback net.

      ${if_name}
           The  hostname associated with the interface of an
           incoming connection.  This macro can be used  for
           SmtpGreetingMessage  and  HReceived  for  virtual
           hosting.  For example:

               O SmtpGreetingMessage=$?{if_name}${if_name}$|$j$. MTA


      ${if_name_out}
           The name of the interface of an outgoing  connec-
           tion.

      ${load_avg}
           The current load average.

      ${mail_addr}
           The  address  part  of the resolved triple of the
           address given for the SMTP MAIL command.  Defined
           in the SMTP server only.

      ${mail_host}
           The  host from the resolved triple of the address
           given for the SMTP MAIL command.  Defined in  the
           SMTP server only.

      ${mail_mailer}
           The  mailer  from  the resolved triple of the ad-
           dress given for the SMTP MAIL  command.   Defined
           in the SMTP server only.

      ${msg_id}
           The value of the Message-Id: header.

      ${msg_size}
           The  value  of the SIZE= parameter, i.e., usually
           the size of the message (in an  ESMTP  dialogue),
           before the message has been collected, thereafter
           the message size as computed by sendmail (and can










Sendmail Installation and Operation Guide          SMM:08-81


           be used in check_compat).

      ${nbadrcpts}
           The  number  of  bad recipients for a single mes-
           sage.

      ${nrcpts}
           The number of validated recipients for  a  single
           message.   Note:  since recipient validation hap-
           pens after check_rcpt has been called, the  value
           in  this  ruleset  is one less than what might be
           expected.

      ${ntries}
           The number of delivery attempts.

      ${opMode}
           The current operation mode (from the -b flag).

      ${quarantine}
           The quarantine reason for the envelope, if it  is
           quarantined.

      ${queue_interval}
           The queue run interval given by the -q flag.  For
           example, -q30m  would  set  ${queue_interval}  to
           "00:30:00".

      ${rcpt_addr}
           The  address  part  of the resolved triple of the
           address given for the SMTP RCPT command.  Defined
           in the SMTP server only after a RCPT command.

      ${rcpt_host}
           The  host from the resolved triple of the address
           given for the SMTP RCPT command.  Defined in  the
           SMTP server only after a RCPT command.

      ${rcpt_mailer}
           The  mailer  from  the resolved triple of the ad-
           dress given for the SMTP RCPT  command.   Defined
           in the SMTP server only after a RCPT command.

      ${server_addr}
           The address of the server of the current outgoing
           SMTP connection.  For LMTP delivery the macro  is
           set to the name of the mailer.

      ${server_name}
           The  name  of  the server of the current outgoing
           SMTP or LMTP connection.












SMM:08-82          Sendmail Installation and Operation Guide


      ${time}
           The output of the  time(3)  function,  i.e.,  the
           number  of  seconds  since  0 hours, 0 minutes, 0
           seconds, January 1, 1970,  Coordinated  Universal
           Time (UTC).

      ${tls_version}
           The  TLS/SSL  version  used  for  the connection,
           e.g., TLSv1, SSLv3, SSLv2; defined after STARTTLS
           has been used.

      ${total_rate}
           The total number of incoming connections over the
           time interval specified by  ConnectionRateWindow-
           Size.

      ${verify}
           The  result  of the verification of the presented
           cert; only defined after STARTTLS has  been  used
           (or attempted).  Possible values are:

               OK           verification succeeded.
               NO           no cert presented.
               NOT          no cert requested.
               FAIL         cert presented but could not be verified,
                            e.g., the signing CA is missing.
               NONE         STARTTLS has not been performed.
               TEMP         temporary error occurred.
               PROTOCOL     some protocol error occurred
                            at the ESMTP level (not TLS).
               SOFTWARE     STARTTLS handshake failed,
                            which is a fatal error for this session,
                            the e-mail will be queued.


           There  are three types of dates that can be used.
      The $a and $b macros are in RFC 822 format; $a is  the
      time as extracted from the "Date:" line of the message
      (if there was one), and $b is  the  current  date  and
      time  (used  for  postmarks).   If  no "Date:" line is
      found in the incoming message, $a is set to  the  cur-
      rent  time also.  The $d macro is equivalent to the $b
      macro in UNIX (ctime) format.

           The macros $w, $j, and $m are set to the identity
      of this host.  Sendmail tries to find the fully quali-
      fied name of the host if at all possible; it does this
      by  calling gethostname(2) to get the current hostname
      and then passing that  to  gethostbyname(3)  which  is
      supposed  to return the canonical version of that host













Sendmail Installation and Operation Guide          SMM:08-83


      name.[17] Assuming this is successful, $j  is  set  to
      the  fully  qualified name and $m is set to the domain
      part of the name (everything  after  the  first  dot).
      The  $w macro is set to the first word (everything be-
      fore the first dot) if you have a level  5  or  higher
      configuration  file;  otherwise, it is set to the same
      value as $j.  If the canonification is not successful,
      it  is  imperative  that the config file set $j to the
      fully qualified domain name[18].

           The  $f  macro  is the id of the sender as origi-
      nally determined; when mailing to a specific host  the
      $g  macro is set to the address of the sender relative
      to the recipient.  For example, if  I  send  to  "bol-
      lard@matisse.CS.Berkeley.EDU"  from  the machine "van-
      gogh.CS.Berkeley.EDU" the $f macro will be "eric"  and
      the $g macro will be "eric@vangogh.CS.Berkeley.EDU."

           The  $x  macro  is  set  to  the full name of the
      sender.  This can be determined in several  ways.   It
      can  be passed as flag to sendmail.  It can be defined
      in the NAME environment variable.  The third choice is
      the value of the "Full-Name:" line in the header if it
      exists, and the fourth choice is the comment field  of
      a "From:" line.  If all of these fail, and if the mes-
      sage is being originated locally,  the  full  name  is
      looked up in the /etc/passwd file.

           When  sending,  the $h, $u, and $z macros get set
      to the host, user, and home directory  (if  local)  of
      the  recipient.  The first two are set from the $@ and
      $: part of the rewriting rules, respectively.

           The $p and $t macros are used  to  create  unique
      strings  (e.g.,  for the "Message-Id:" field).  The $i
      macro is set to the queue id on this host; if put into
      the  timestamp  line  it  can  be extremely useful for
      tracking messages.  The $v macro is set to be the ver-
      sion number of sendmail; this is normally put in time-
      stamps and has been proven extremely useful for debug-
      ging.

           The $c field is set to the "hop count," i.e., the
      number of times this message has been processed.  This
      can  be  determined by the -h flag on the command line
      or by counting the timestamps in the message.
____________________
   [17]For example, on some systems gethostname might return
"foo"  which  would be mapped to "foo.bar.com" by gethostby-
name.
   [18]Older versions of sendmail didn't  pre-define  $j  at
all, so up until 8.6, config files always had to define $j.











SMM:08-84          Sendmail Installation and Operation Guide


           The $r and $s fields are set to the protocol used
      to communicate with sendmail and the sending hostname.
      They can be set together using  the  -p  command  line
      flag or separately using the -M or -oM flags.

           The  $_  is  set to a validated sender host name.
      If the sender is running an RFC 1413  compliant  IDENT
      server  and the receiver has the IDENT protocol turned
      on, it will include the user name on that host.

           The    ${client_name},    ${client_addr},     and
      ${client_port}  macros  are  set to the name, address,
      and port number of the SMTP  client  who  is  invoking
      sendmail  as  a  server.   These  can  be  used in the
      check_* rulesets (using  the  $&  deferred  evaluation
      form, of course!).

   5.3.  C and F -- Define Classes

           Classes of phrases may be defined to match on the
      left hand side of rewriting rules, where a "phrase" is
      a  sequence  of characters that does not contain space
      characters.  For example a class of  all  local  names
      for  this  site  might  be created so that attempts to
      send to oneself can be eliminated.  These  can  either
      be  defined directly in the configuration file or read
      in from another file.  Classes are named as  a  single
      letter  or  a word in {braces}.  Class names beginning
      with lower case letters and special characters are re-
      served  for  system  use.   Classes  defined in config
      files may be given names from the set  of  upper  case
      letters  for  short  names  or beginning with an upper
      case letter for long names.

           The syntax is:

          Ccphrase1 phrase2...
          Fcfile
          Fc|program
          Fc[mapkey]@mapclass:mapspec

      The first form defines the class c to match any of the
      named  words.  If phrase1 or phrase2 is another class,
      e.g., $=S, the contents of class S are added to  class
      c.   It  is  permissible  to split them among multiple
      lines; for example, the two forms:

          CHmonet ucbmonet

      and

          CHmonet
          CHucbmonet










Sendmail Installation and Operation Guide          SMM:08-85


      are equivalent.  The ``F'' forms read the elements  of
      the class c from the named file, program, or map spec-
      ification.  Each element should be listed on  a  sepa-
      rate  line.   To  specify an optional file, use ``-o''
      between the class name and the file name, e.g.,

          Fc -o /path/to/file

      If the file can't be used, sendmail will not  complain
      but silently ignore it.  The map form should be an op-
      tional map key, an at sign, and a map  class  followed
      by the specification for that map.  Examples include:

          F{VirtHosts}@ldap:-k (&(objectClass=virtHosts)(host=*)) -v host
          F{MyClass}foo@hash:/etc/mail/classes

      will  fill  the  class  $={VirtHosts} from an LDAP map
      lookup and $={MyClass} from a hash database map lookup
      of  the foo.  There is also a built-in schema that can
      be accessed by only specifying:

          F{ClassName}@LDAP

      This will tell sendmail to use the default schema:

          -k (&(objectClass=sendmailMTAClass)
               (sendmailMTAClassName=ClassName)
               (|(sendmailMTACluster=${sendmailMTACluster})
                 (sendmailMTAHost=$j)))
          -v sendmailMTAClassValue

      Note that the lookup is only  done  when  sendmail  is
      initially started.

           Elements  of classes can be accessed in rules us-
      ing $= or $~.  The $~ (match  entries  not  in  class)
      only  matches a single word; multi-word entries in the
      class are ignored in this context.

           Some classes have internal meaning to sendmail:

      $=e  contains the Content-Transfer-Encodings that  can
           be 8->7 bit encoded.  It is predefined to contain
           "7bit", "8bit", and "binary".

      $=k  set to be the same as $k, that is, the UUCP  node
           name.

      $=m  set  to  the set of domains by which this host is
           known, initially just $m.

      $=n  can be set to the set of MIME body types that can
           never be eight to seven bit encoded.  It defaults










SMM:08-86          Sendmail Installation and Operation Guide


           to "multipart/signed".  Message types "message/*"
           and  "multipart/*"  are  never  encoded directly.
           Multipart  messages  are  always  handled  recur-
           sively.   The  handling of message/* messages are
           controlled by class $=s.

      $=q  A set of Content-Types that will never be encoded
           as  base64 (if they have to be encoded, they will
           be encoded as  quoted-printable).   It  can  have
           primary  types (e.g., "text") or full types (such
           as "text/plain").

      $=s  contains the set of subtypes of message that  can
           be  treated  recursively.  By default it contains
           only "rfc822".  Other "message/*" types cannot be
           8->7  bit encoded.  If a message containing eight
           bit data is sent to a seven bit  host,  and  that
           message  cannot  be  encoded  into seven bits, it
           will be stripped to 7 bits.

      $=t  set to the set of trusted users by the T configu-
           ration  line.   If you want to read trusted users
           from a file, use Ft/file/name.

      $=w  set to be the set of all names this host is known
           by.  This can be used to match local hostnames.

      $={persistentMacros}
           set  to  the  macros  that should be saved across
           queue runs.  Care should  be  taken  when  adding
           macro names to this class.

           Sendmail  can  be  compiled  to  allow a scanf(3)
      string on the F line.  This  lets  you  do  simplistic
      parsing  of  text files.  For example, to read all the
      user names in your  system  /etc/passwd  file  into  a
      class, use

          FL/etc/passwd %[^:]

      which reads every line up to the first colon.

   5.4.  M -- Define Mailer

           Programs and interfaces to mailers are defined in
      this line.  The format is:

          Mname, {field=value}*

      where name is the name of the mailer (used  internally
      only)  and the "field=name" pairs define attributes of
      the mailer.  Fields are:











Sendmail Installation and Operation Guide          SMM:08-87


          Path      The pathname of the mailer
          Flags     Special flags for this mailer
          Sender    Rewriting set(s) for sender addresses
          Recipient Rewriting set(s) for recipient addresses
          recipientsMaximum number of recipients per connection
          Argv      An argument vector to pass to this mailer
          Eol       The end-of-line string for this mailer
          Maxsize   The maximum message length to this mailer
          maxmessagesThe maximum message deliveries per connection
          Linelimit The maximum line length in the message body
          Directory The working directory for the mailer
          Userid    The default user and group id to run as
          Nice      The nice(2) increment for the mailer
          Charset   The default character set for 8-bit characters
          Type      Type information for DSN diagnostics
          Wait      The maximum time to wait for the mailer
          QueuegroupThe default queue group for the mailer
          /         The root directory for the mailer

      Only the first character of the field name is  checked
      (it's case-sensitive).

           The  following flags may be set in the mailer de-
      scription.  Any other flags may be used freely to con-
      ditionally  assign  headers  to  messages destined for
      particular mailers.  Flags marked with * are  not  in-
      terpreted  by  the sendmail binary; these are the con-
      ventionally used to correlate to the flags portion  of
      the  H line.  Flags marked with # apply to the mailers
      for the sender address rather than the usual recipient
      mailers.

      a   Run  Extended  SMTP  (ESMTP)  protocol (defined in
          RFCs 1869, 1652, and 1870).  This flag defaults on
          if  the  SMTP  greeting  message includes the word
          "ESMTP".

      A   Look up the user (address) part  of  the  resolved
          mailer  triple,  in  the alias database.  Normally
          this is only set for local mailers.

      b   Force a blank line on the end of a message.   This
          is intended to work around some stupid versions of
          /bin/mail that require a blank line,  but  do  not
          provide  it  themselves.  It would not normally be
          used on network mail.

      B   Strip leading backslashes (\) off of the  address;
          this  is  a  subset  of the functionality of the s
          flag.

      c   Do not include comments in addresses.  This should
          only  be  used if you have to work around a remote










SMM:08-88          Sendmail Installation and Operation Guide


          mailer  that  gets  confused  by  comments.   This
          strips addresses of the form "Phrase <address>" or
          "address (Comment)" down to just "address".

      C#  If mail is received from a mailer with  this  flag
          set,  any addresses in the header that do not have
          an at sign ("@") after being rewritten by  ruleset
          three  will  have  the  "@domain"  clause from the
          sender envelope address tacked  on.   This  allows
          mail with headers of the form:

              From: usera@hosta
              To: userb@hostb, userc

          to be rewritten as:

              From: usera@hosta
              To: userb@hostb, userc@hosta

          automatically.   However,  it  doesn't really work
          reliably.

      d   Do not include angle brackets around route-address
          syntax  addresses.  This is useful on mailers that
          are going to pass addresses to a shell that  might
          interpret angle brackets as I/O redirection.  How-
          ever, it does  not  protect  against  other  shell
          metacharacters.  Therefore, passing addresses to a
          shell should not be considered secure.

      D*  This mailer wants a "Date:" header line.

      e   This mailer is expensive to connect to, so try  to
          avoid  connecting  normally; any necessary connec-
          tion will occur during a queue run.  See also  op-
          tion HoldExpensive.

      E   Escape lines beginning with "From " in the message
          with a `>' sign.

      f   The mailer wants a -f from flag, but only if  this
          is  a  network forward operation (i.e., the mailer
          will give an error if the executing user does  not
          have special permissions).

      F*  This mailer wants a "From:" header line.

      g   Normally,   sendmail  sends  internally  generated
          email (e.g., error messages) using the null return
          address  as  required  by RFC 1123.  However, some
          mailers don't accept a null  return  address.   If
          necessary, you can set the g flag to prevent send-
          mail from obeying the  standards;  error  messages










Sendmail Installation and Operation Guide          SMM:08-89


          will  be sent as from the MAILER-DAEMON (actually,
          the value of the $n macro).

      h   Upper case should be preserved in host names  (the
          $@  portion  of  the  mailer triplet resolved from
          ruleset 0) for this mailer.

      i   Do User Database rewriting on envelope sender  ad-
          dress.

      I   This flag is deprecated and will be removed from a
          future version.  This mailer will be speaking SMTP
          to  another sendmail -- as such it can use special
          protocol features.  This flag should not  be  used
          except for debugging purposes because it uses VERB
          as SMTP command.

      j   Do User Database rewriting on recipients  as  well
          as senders.

      k   Normally  when  sendmail  connects  to  a host via
          SMTP, it checks to make sure that this isn't acci-
          dently the same host name as might happen if send-
          mail is misconfigured or if  a  long-haul  network
          interface is set in loopback mode.  This flag dis-
          ables the loopback check.  It should only be  used
          under very unusual circumstances.

      K   Currently unimplemented.  Reserved for chunking.

      l   This mailer is local (i.e., final delivery will be
          performed).

      L   Limit the line lengths as specified  in  RFC  821.
          This  deprecated  option should be replaced by the
          L= mail declaration.  For historic reasons, the  L
          flag also sets the 7 flag.

      m   This mailer can send to multiple users on the same
          host in one transaction.  When a $u  macro  occurs
          in  the  argv  part of the mailer definition, that
          field will be repeated as necessary for all quali-
          fying users.  Removing this flag can defeat dupli-
          cate supression on a remote site as each recipient
          is sent in a separate transaction.

      M*  This mailer wants a "Message-Id:" header line.

      n   Do  not  insert  a  UNIX-style  "From" line on the
          front of the message.

      o   Always run as the owner of the recipient  mailbox.
          Normally  sendmail  runs as the sender for locally










SMM:08-90          Sendmail Installation and Operation Guide


          generated mail or as "daemon" (actually, the  user
          specified in the u option) when delivering network
          mail.  The normal behavior is required by most lo-
          cal  mailers,  which  will  not allow the envelope
          sender address to be set unless the mailer is run-
          ning  as  daemon.   This  flag is ignored if the S
          flag is set.

      p   Use the route-addr style reverse-path in the  SMTP
          "MAIL  FROM:"  command rather than just the return
          address; although this is required in RFC 821 sec-
          tion  3.1, many hosts do not process reverse-paths
          properly.  Reverse-paths are  officially  discour-
          aged by RFC 1123.

      P*  This mailer wants a "Return-Path:" line.

      q   When  an  address  that resolves to this mailer is
          verified (SMTP VRFY  command),  generate  250  re-
          sponses instead of 252 responses.  This will imply
          that the address is local.

      r   Same as f, but sends a -r flag.

      R   Open SMTP connections from a "secure"  port.   Se-
          cure ports aren't (secure, that is) except on UNIX
          machines, so it is unclear  that  this  adds  any-
          thing.   sendmail  must  be  running as root to be
          able to use this flag.

      s   Strip quote characters (" and \) off  of  the  ad-
          dress before calling the mailer.

      S   Don't  reset the userid before calling the mailer.
          This would be used in a secure  environment  where
          sendmail ran as root.  This could be used to avoid
          forged addresses.  If the U= field is also  speci-
          fied, this flag causes the effective user id to be
          set to that user.

      u   Upper case should be preserved in user  names  for
          this  mailer.   Standards  require preservation of
          case in the local part of  addresses,  except  for
          those  address  for  which your system accepts re-
          sponsibility.  RFC 2142 provides a  long  list  of
          addresses  which  should  be case insensitive.  If
          you use this flag, you may be violating RFC  2142.
          Note  that  postmaster is always treated as a case
          insensitive address regardless of this flag.

      U   This mailer wants UUCP-style "From" lines with the
          ugly "remote from <host>" on the end.











Sendmail Installation and Operation Guide          SMM:08-91


      w   The  user  must  have  a valid account on this ma-
          chine, i.e., getpwnam must succeed.  If  not,  the
          mail is bounced.  See also the MailBoxDatabase op-
          tion.  This is required to get ".forward" capabil-
          ity.

      W   Ignore long term host status information (see Sec-
          tion "Persistent Host Status Information").

      x*  This mailer wants a "Full-Name:" header line.

      X   This mailer wants to use the hidden dot  algorithm
          as  specified  in RFC 821; basically, any line be-
          ginning  with  a  dot  will  have  an  extra   dot
          prepended (to be stripped at the other end).  This
          insures that lines in the message containing a dot
          will not terminate the message prematurely.

      z   Run  Local  Mail  Transfer Protocol (LMTP) between
          sendmail and the local mailer.  This is a  variant
          on  SMTP  defined in RFC 2033 that is specifically
          designed for delivery to a local mailbox.

      Z   Apply DialDelay (if set) to this mailer.

      0   Don't look  up  MX  records  for  hosts  sent  via
          SMTP/LMTP.  Do not apply FallbackMXhost either.

      1   Don't send null characters ('\0') to this mailer.

      2   Don't  use  ESMTP  even if offered; this is useful
          for broken systems that offer ESMTP  but  fail  on
          EHLO (without recovering when HELO is tried next).

      3   Extend the list of characters converted to =XX no-
          tation when converting to Quoted-Printable to  in-
          clude  those  that don't map cleanly between ASCII
          and EBCDIC.  Useful if you have IBM mainframes  on
          site.

      5   If no aliases are found for this address, pass the
          address through ruleset 5 for  possible  alternate
          resolution.   This is intended to forward the mail
          to an alternate delivery spot.

      6   Strip headers to seven bits.

      7   Strip all output to seven bits.  This is  the  de-
          fault  if  the  L flag is set.  Note that clearing
          this option is not sufficient to  get  full  eight
          bit data passed through sendmail.  If the 7 option
          is set, this is essentially always set, since  the
          eighth  bit was stripped on input.  Note that this










SMM:08-92          Sendmail Installation and Operation Guide


          option will only impact messages that didn't  have
          8->7 bit MIME conversions performed.

      8   If set, it is acceptable to send eight bit data to
          this mailer; the usual attempt to do 8->7 bit MIME
          conversions will be bypassed.

      9   If  set,  do  limited  7->8  bit MIME conversions.
          These conversions are limited to text/plain data.

      :   Check addresses to see if they begin  ":include:";
          if  they  do,  convert  them  to  the  "*include*"
          mailer.

      |   Check addresses to see if they begin with  a  `|';
          if they do, convert them to the "prog" mailer.

      /   Check  addresses  to see if they begin with a `/';
          if they do, convert them to the "*file*" mailer.

      @   Look up addresses in the user database.

      %   Do not attempt delivery on initial  receipt  of  a
          message or on queue runs unless the queued message
          is selected using one of the -qI/-qR/-qS queue run
          modifiers or an ETRN request.

      !   Disable  an  MH  hack that drops an explicit From:
          header if it is the same as  what  sendmail  would
          generate.

           Configuration  files  prior to level 6 assume the
      `A', `w', `5', `:', `|', `/', and `@' options  on  the
      mailer named "local".

           The  mailer  with the special name "error" can be
      used to generate a user error.   The  (optional)  host
      field  is  an exit status to be returned, and the user
      field is a message to be printed.  The exit status may
      be numeric or one of the values USAGE, NOUSER, NOHOST,
      UNAVAILABLE, SOFTWARE, TEMPFAIL, PROTOCOL,  or  CONFIG
      to  return  the corresponding EX_ exit code, or an en-
      hanced error code as described in RFC  1893,  Enhanced
      Mail System Status Codes.  For example, the entry:

          $#error $@ NOHOST $: Host unknown in this domain

      on the RHS of a rule will cause the specified error to
      be generated and the "Host unknown" exit status to  be
      returned  if  the  LHS  matches.   This mailer is only
      functional in rulesets 0, 5, or  one  of  the  check_*
      rulesets.  The host field can also contain the special
      token   quarantine   which   instructs   sendmail   to










Sendmail Installation and Operation Guide          SMM:08-93


      quarantine the current message.

           The mailer with the special name "discard" causes
      any mail sent to it  to  be  discarded  but  otherwise
      treated  as  though  it  were  successfully delivered.
      This mailer cannot be used in ruleset 0, only  in  the
      various address checking rulesets.

           The mailer named "local" must be defined in every
      configuration file.  This is  used  to  deliver  local
      mail, and is treated specially in several ways.  Addi-
      tionally, three other mailers named "prog",  "*file*",
      and "*include*" may be defined to tune the delivery of
      messages to programs, files, and :include:  lists  re-
      spectively.  They default to:

          Mprog, P=/bin/sh, F=lsoDq9, T=DNS/RFC822/X-Unix, A=sh -c $u
          M*file*, P=[FILE], F=lsDFMPEouq9, T=DNS/RFC822/X-Unix, A=FILE $u
          M*include*, P=/dev/null, F=su, A=INCLUDE $u


           Builtin  pathnames are [FILE] and [IPC], the for-
      mer is used for delivery to files, the latter for  de-
      livery  via  interprocess  communication.  For mailers
      that use [IPC] as pathname the  argument  vector  (A=)
      must  start with TCP or FILE for delivery via a TCP or
      a Unix domain socket.  If TCP is used, the second  ar-
      gument  must  be the name of the host to contact.  Op-
      tionally a third argument can be  used  to  specify  a
      port, the default is smtp (port 25).  If FILE is used,
      the second argument must be the name of the  Unix  do-
      main socket.

           If  the  argument vector does not contain $u then
      sendmail will speak SMTP (or LMTP if the mailer flag z
      is specified) to the mailer.

           If  no  Eol field is defined, then the default is
      "\r\n" for SMTP mailers and "\n" of others.

           The Sender and Recipient rewriting sets  may  ei-
      ther  be  a  simple ruleset id or may be two ids sepa-
      rated by a slash; if so, the first  rewriting  set  is
      applied  to  envelope  addresses and the second is ap-
      plied to headers.  Setting any value to zero  disables
      corresponding mailer-specific rewriting.

           The  Directory is actually a colon-separated path
      of directories to try.  For  example,  the  definition
      "D=$z:/"  first  tries  to  execute in the recipient's
      home directory; if that is not available, it tries  to
      execute  in  the  root of the filesystem.  This is in-
      tended to be used only on  the  "prog"  mailer,  since










SMM:08-94          Sendmail Installation and Operation Guide


      some  shells  (such  as csh) refuse to execute if they
      cannot read the current directory.   Since  the  queue
      directory  is  not  normally  readable by unprivileged
      users csh scripts as recipients can fail.

           The Userid specifies the default user  and  group
      id  to  run  as,  overriding  the  DefaultUser  option
      (q.v.).  If the S mailer flag is also specified,  this
      user  and  group  will be set as the effective uid and
      gid for the process.  This may be given as  user:group
      to  set  both  the user and group id; either may be an
      integer or a symbolic name to  be  looked  up  in  the
      passwd  and  group files respectively.  If only a sym-
      bolic user name is specified,  the  group  id  in  the
      passwd file for that user is used as the group id.

           The  Charset field is used when converting a mes-
      sage to MIME; this is the character set  used  in  the
      Content-Type:  header.   If  this  is not set, the De-
      faultCharset option is used, and if that is  not  set,
      the value "unknown-8bit" is used.  WARNING: this field
      applies to the sender's mailer,  not  the  recipient's
      mailer.   For  example, if the envelope sender address
      lists an address on the local network and the  recipi-
      ent  is on an external network, the character set will
      be set from the Charset= field for the  local  network
      mailer, not that of the external network mailer.

           The Type= field sets the type information used in
      MIME error messages as defined by RFC 1894.  It is ac-
      tually three values separated by slashes: the MTA-type
      (that is, the description of how hosts are named), the
      address  type  (the  description of e-mail addresses),
      and the diagnostic type (the description of error  di-
      agnostic  codes).   Each of these must be a registered
      value  or   begin   with   "X-".    The   default   is
      "dns/rfc822/smtp".

           The m= field specifies the maximum number of mes-
      sages to attempt to deliver on a single SMTP  or  LMTP
      connection.  The default is infinite.

           The  r= field specifies the maximum number of re-
      cipients to attempt to deliver in a  single  envelope.
      It defaults to 100.

           The  /=  field specifies a new root directory for
      the mailer.  The  path  is  macro  expanded  and  then
      passed  to  the "chroot" system call.  The root direc-
      tory is changed before the  Directory  field  is  con-
      sulted or the uid is changed.












Sendmail Installation and Operation Guide          SMM:08-95


           The  Wait=  field  specifies  the maximum time to
      wait for the mailer to return after sending  all  data
      to  it.  This applies to mailers that have been forked
      by sendmail.

           The Queuegroup= field specifies the default queue
      group  in  which received mail should be queued.  This
      can be overridden by other means as explained in  sec-
      tion ``Queue Groups and Queue Directories''.

   5.5.  H -- Define Header

           The  format of the header lines that sendmail in-
      serts into the message are defined by the H line.  The
      syntax of this line is one of the following:

          Hhname: htemplate


          H[?mflags?]hname: htemplate


          H[?${macro}?]hname: htemplate

      Continuation lines in this spec are reflected directly
      into the outgoing message.  The htemplate is macro-ex-
      panded  before  insertion  into  the  message.  If the
      mflags (surrounded by question marks)  are  specified,
      at  least one of the specified flags must be stated in
      the mailer definition for this header to be  automati-
      cally  output.   If a ${macro} (surrounded by question
      marks) is specified, the header will be  automatically
      output  if the macro is set.  The macro may be set us-
      ing any of the normal  methods,  including  using  the
      macro storage map in a ruleset.  If one of these head-
      ers is in the input it is reflected to the output  re-
      gardless  of  these  flags  or  macros.   Notice: If a
      ${macro} is used to set a header, then it is useful to
      add  that  macro  to  class $={persistentMacros} which
      consists of the macros that  should  be  saved  across
      queue runs.

           Some  headers have special semantics that will be
      described later.

           A secondary syntax allows validation  of  headers
      as they are being read.  To enable validation, use:

          HHeader: $>Ruleset
          HHeader: $>+Ruleset

      The  indicated  Ruleset  is  called  for the specified
      Header, and can return $#error to reject or quarantine










SMM:08-96          Sendmail Installation and Operation Guide


      the  message  or  $#discard to discard the message (as
      with the other check_*  rulesets).   The  ruleset  re-
      ceives  the  header  field-body as argument, i.e., not
      the header field-name; see also ${hdr_name} and ${cur-
      rHeader}.   The  header  is  treated  as  a structured
      field, that is, text in parentheses is deleted  before
      processing, unless the second form $>+ is used.  Note:
      only one ruleset can  be  associated  with  a  header;
      sendmail will silently ignore multiple entries.

           For example, the configuration lines:

          HMessage-Id: $>CheckMessageId

          SCheckMessageId
          R< $+ @ $+  >$@ OK
          R$*       $#error $: Illegal Message-Id header

      would refuse any message that had a Message-Id: header
      of any of the following forms:

          Message-Id: <>
          Message-Id: some text
          Message-Id: <legal text@domain> extra crud

      A default ruleset that is  called  for  headers  which
      don't  have a specific ruleset defined for them can be
      specified by:

          H*: $>Ruleset

      or

          H*: $>+Ruleset


   5.6.  O -- Set Option

           There are a number of global options that can  be
      set  from  a  configuration  file.  Options are repre-
      sented by full words; some are also  representable  as
      single  characters for back compatibility.  The syntax
      of this line is:

          O  option=value

      This sets option option to be value.  Note that  there
      must be a space between the letter `O' and the name of
      the option.  An older version is:

          Oovalue

      where the option o is a single  character.   Depending










Sendmail Installation and Operation Guide          SMM:08-97


      on  the  option,  value may be a string, an integer, a
      boolean (with legal values "t", "T", "f", or "F";  the
      default is TRUE), or a time interval.

           All  filenames used in options should be absolute
      paths, i.e., starting with  '/'.   Relative  filenames
      most  likely  cause surprises during operation (unless
      otherwise noted).

           The options supported (with the old, one  charac-
      ter names in brackets) are:

      AliasFile=spec, spec, ...
                [A]  Specify  possible  alias file(s).  Each
                spec should be in the format ``class: info''
                where  class:  is  optional  and defaults to
                ``implicit''.  Note that  info  is  required
                for  all  classes  except  "ldap".   For the
                "ldap" class, if info is  not  specified,  a
                default info value is used as follows:

                    -k (&(objectClass=sendmailMTAAliasObject)
                         (sendmailMTAAliasName=aliases)
                         (|(sendmailMTACluster=${sendmailMTACluster})
                           (sendmailMTAHost=$j))
                         (sendmailMTAKey=%0))
                    -v sendmailMTAAliasValue

                Depending on how sendmail is compiled, valid
                classes are  "implicit"  (search  through  a
                compiled-in  list  of  alias file types, for
                back compatibility),  "hash"  (if  NEWDB  is
                specified), "btree" (if NEWDB is specified),
                "dbm" (if NDBM is specified), "stab" (inter-
                nal symbol table -- not normally used unless
                you have no  other  database  lookup),  "se-
                quence"  (use  a sequence of maps previously
                declared), "ldap" (if LDAPMAP is specified),
                or  "nis"  (if NIS is specified).  If a list
                of specs  are  provided,  sendmail  searches
                them in order.

      AliasWait=timeout
                [a]  If  set,  wait up to timeout (units de-
                fault to minutes) for an "@:@" entry to  ex-
                ist  in  the  alias database before starting
                up.  If it does not appear  in  the  timeout
                interval issue a warning.

      AllowBogusHELO
                [no short name] If set, allow HELO SMTP com-
                mands that don't include a host name.   Set-
                ting  this  violates RFC 1123 section 5.2.5,










SMM:08-98          Sendmail Installation and Operation Guide


                but is necessary to interoperate  with  sev-
                eral  SMTP clients.  If there is a value, it
                is still checked for legitimacy.

      AuthMaxBits=N
                [no short name] Limit the maximum encryption
                strength for the security layer in SMTP AUTH
                (SASL). Default  is  essentially  unlimited.
                This  allows  to turn off additional encryp-
                tion in SASL if STARTTLS is already encrypt-
                ing  the communication, because the existing
                encryption strength is  taken  into  account
                when  choosing an algorithm for the security
                layer.  For example, if STARTTLS is used and
                the  symmetric  cipher is 3DES, then the the
                keylength (in bits) is 168.   Hence  setting
                AuthMaxBits  to 168 will disable any encryp-
                tion in SASL.

      AuthMechanisms
                [no short name] List of authentication mech-
                anisms  for AUTH (separated by spaces).  The
                advertised list of authentication mechanisms
                will  be  the  intersection of this list and
                the list of available mechanisms  as  deter-
                mined  by the Cyrus SASL library.  If START-
                TLS is active, EXTERNAL  will  be  added  to
                this  list.   In  that  case,  the  value of
                {cert_subject} is used as authentication id.

      AuthOptions
                [no short name] List  of  options  for  SMTP
                AUTH  consisting  of  single characters with
                intervening white space or commas.





























Sendmail Installation and Operation Guide          SMM:08-99


                    A   Use the AUTH= parameter for the MAIL FROM
                        command only when authentication succeeded.
                        This can be used as a workaround for broken
                        MTAs that do not implement RFC 2554 correctly.
                    a   protection from active (non-dictionary) attacks
                        during authentication exchange.
                    c   require mechanisms which pass client credentials,
                        and allow mechanisms which can pass credentials
                        to do so.
                    d   don't permit mechanisms susceptible to passive
                        dictionary attack.
                    f   require forward secrecy between sessions
                        (breaking one won't help break next).
                    m   require mechanisms which provide mutual authentication
                        (only available if using Cyrus SASL v2 or later).
                    p   don't permit mechanisms susceptible to simple
                        passive attack (e.g., PLAIN, LOGIN), unless a
                        security layer is active.
                    y   don't permit mechanisms that allow anonymous login.

                The first option applies to  sendmail  as  a
                client, the others to a server.  Example:

                    O AuthOptions=p,y

                would  disallow  ANONYMOUS as AUTH mechanism
                and would allow PLAIN and LOGIN  only  if  a
                security  layer (e.g., provided by STARTTLS)
                is already active.  The  options  'a',  'c',
                'd',  'f',  'p', and 'y' refer to properties
                of the selected SASL  mechanisms.   Explana-
                tions  of  these  properties can be found in
                the Cyrus SASL documentation.

      AuthRealm [no short  name]  The  authentication  realm
                that  is  passed  to the Cyrus SASL library.
                If no realm is specified, $j is  used.   See
                also KNOWNBUGS.

      BadRcptThrottle=N
                [no  short  name]  If  set and the specified
                number of recipients in a single SMTP trans-
                action  have  been  rejected,  sleep for one
                second after each subsequent RCPT command in
                that transaction.

      BlankSub=c
                [B]  Set the blank substitution character to
                c.  Unquoted spaces  in  addresses  are  re-
                placed by this character.  Defaults to space
                (i.e., no change is made).












SMM:08-100         Sendmail Installation and Operation Guide


      CACertPath
                [no short name] Path to directory with  cer-
                tificates  of CAs.  This directory directory
                must contain the hashes of each CA  certifi-
                cate as filenames (or as links to them).

      CACertFile
                [no  short name] File containing one or more
                CA certificates; see section about  STARTTLS
                for more information.

      CertFingerprintAlgorithm
                Specify  the  fingerprint algorithm (digest)
                to use for the presented cert.  If  the  op-
                tion  is  not set, md5 is used and the macro
                contains the cert fingerprint.  If  the  op-
                tion  is explicitly set, the specified algo-
                rithm (e.g., sha1) is  used  and  the  macro
                ${cert_fp} contains the cert fingerprint.

      CipherList
                Specify  cipher  list for STARTTLS.  See ci-
                phers(1) for possible values.

      CheckAliases
                [n] Validate the RHS  of  aliases  when  re-
                building the alias database.

      CheckpointInterval=N
                [C]  Checkpoints  the queue every N (default
                10) addresses sent.  If your system  crashes
                during  delivery  to a large list, this pre-
                vents retransmission to any but the  last  N
                recipients.

      ClassFactor=fact
                [z]  The  indicated  factor is multiplied by
                the message class (determined by the  Prece-
                dence:  field  in  the user header and the P
                lines in the configuration  file)  and  sub-
                tracted  from  the priority.  Thus, messages
                with a higher  Priority:  will  be  favored.
                Defaults to 1800.

      ClientCertFile
                [no short name] File containing the certifi-
                cate of the client, i.e.,  this  certificate
                is  used  when  sendmail acts as client (for
                STARTTLS).

      ClientKeyFile
                [no short name] File containing the  private
                key belonging to the client certificate (for










Sendmail Installation and Operation Guide         SMM:08-101


                STARTTLS if sendmail runs as client).

      ClientPortOptions=options
                [O] Set client SMTP  options.   The  options
                are  key=value  pairs  separated  by commas.
                Known keys are:

                    Port      Name/number of source port for connection (defaults to any free port)
                    Addr      Address mask (defaults INADDR_ANY)
                    Family    Address family (defaults to INET)
                    SndBufSizeSize of TCP send buffer
                    RcvBufSizeSize of TCP receive buffer
                    Modifier  Options (flags) for the client

                The Address mask may be a numeric address in
                IPv4  dot notation or IPv6 colon notation or
                a network name.  Note that if a network name
                is  specified, only the first IP address re-
                turned for it will be used.  This may  cause
                indeterminate  behavior  for  network  names
                that resolve to multiple addresses.   There-
                fore,  use  of  an  address  is recommended.
                Modifier can be the following character:

                    h         use name of interface for HELO command
                    A         don't use AUTH when sending e-mail
                    S         don't use STARTTLS when sending e-mail

                If ``h'' is set, the name  corresponding  to
                the outgoing interface address (whether cho-
                sen via the Connection parameter or the  de-
                fault)  is  used  for the HELO/EHLO command.
                However, the name  must  not  start  with  a
                square  bracket and it must contain at least
                one dot.  This is a simple test whether  the
                name  is not an IP address (in square brack-
                ets) but a qualified  hostname.   Note  that
                multiple  ClientPortOptions settings are al-
                lowed in order to  give  settings  for  each
                protocol  family  (e.g., one for Family=inet
                and one for  Family=inet6).   A  restriction
                placed  on  one family only affects outgoing
                connections on that particular family.

      ClientSSLOptions
                A space or comma separated list of  SSL  re-
                lated  options  for  the  client  side.  See
                SSL_CTX_set_options(3)  for  a   list;   the
                available  values depend on the OpenSSL ver-
                sion against which sendmail is compiled.  By
                default,      SSL_OP_ALL     SSL_OP_NO_SSLv2
                SSL_OP_NO_TICKET -SSL_OP_TLSEXT_PADDING  are
                used   (if  those  options  are  available).










SMM:08-102         Sendmail Installation and Operation Guide


                Options can be cleared  by  preceeding  them
                with  a  minus sign.  It is also possible to
                specify numerical values, e.g., -0x0010.

      ColonOkInAddr
                [no short name] If set, colons  are  accept-
                able     in    e-mail    addresses    (e.g.,
                "host:user").  If not set,  colons  indicate
                the  beginning  of a RFC 822 group construct
                ("groupname:  member1,  member2,  ...   mem-
                berN;").   Doubled colons are always accept-
                able ("nodename::user")  and  proper  route-
                addr    nesting    is   understood   ("<@re-
                lay:user@host>").  Furthermore, this  option
                defaults  on  if  the  configuration version
                level is less than 6 (for  back  compatibil-
                ity).  However, it must be off for full com-
                patibility with RFC 822.

      ConnectionCacheSize=N
                [k] The maximum number of  open  connections
                that  will be cached at a time.  The default
                is one.  This  delays  closing  the  current
                connection  until  either this invocation of
                sendmail needs to connect to another host or
                it  terminates.  Setting it to zero defaults
                to the old behavior,  that  is,  connections
                are closed immediately.  Since this consumes
                file  descriptors,  the   connection   cache
                should  be kept small: 4 is probably a prac-
                tical maximum.

      ConnectionCacheTimeout=timeout
                [K] The maximum amount of time a cached con-
                nection  will  be  permitted to idle without
                activity.  If this  time  is  exceeded,  the
                connection   is  immediately  closed.   This
                value should be small (on the order  of  ten
                minutes).   Before  sendmail  uses  a cached
                connection, it always sends a  RSET  command
                to  check  the connection; if this fails, it
                reopens the connection.  This keeps your end
                from  failing  if  the  other end times out.
                The point of this option is  to  be  a  good
                network  neighbor  and avoid using up exces-
                sive resources on the other  end.   The  de-
                fault is five minutes.

      ConnectOnlyTo=address
                [no short name] This can be used to override
                the connection  address  (for  testing  pur-
                poses).











Sendmail Installation and Operation Guide         SMM:08-103


      ConnectionRateThrottle=N
                [no  short name] If set to a positive value,
                allow no more than N incoming connections in
                a one second period per daemon.  This is in-
                tended to flatten out peaks  and  allow  the
                load  average  checking to cut in.  Defaults
                to zero (no limits).

      ConnectionRateWindowSize=N
                [no short name] Define the length of the in-
                terval for which the number of incoming con-
                nections is maintained.  The default  is  60
                seconds.

      ControlSocketName=name
                [no  short  name] Name of the control socket
                for daemon management.  A  running  sendmail
                daemon  can be controlled through this named
                socket.   Available  commands   are:   help,
                mstat,  restart,  shutdown, and status.  The
                status command returns the current number of
                daemon  children, the maximum number of dae-
                mon  children,  the  free  disk  space   (in
                blocks) of the queue directory, and the load
                average of the machine expressed as an inte-
                ger.   If not set, no control socket will be
                available.  Solaris  and  pre-4.4BSD  kernel
                users should see the note in sendmail/README
                .

      CRLFile=name
                [no short name] Name of file  that  contains
                certificate  revocation  status,  useful for
                X.509v3 authentication.   CRL  checking  re-
                quires   at  least  OpenSSL  version  0.9.7.
                Note: if a CRLFile is specified but the file
                is unusable, STARTTLS is disabled.

      DHParameters
                This option applies to the server side only.
                Possible values are:

                    5                   use precomputed 512 bit prime.
                    1                   generate 1024 bit prime
                    2                   generate 2048 bit prime.
                    i                   use included precomputed 2048 bit prime (default).
                    none                do not use Diffie-Hellman.
                    /path/to/file       load prime from file.

                This is only required if a ciphersuite  con-
                taining  DSA/DH  is  used.   The  default is
                ``i'' which  selects  a  precomputed,  fixed
                2048  bit prime.  If ``5'' is selected, then










SMM:08-104         Sendmail Installation and Operation Guide


                precomputed, fixed primes are  used.   Note:
                this  option should not be used (unless nec-
                essary for compatibility with old  implemen-
                tations).   If  ``1''  or ``2'' is selected,
                then  prime  values  are   computed   during
                startup.   Note:  this  operation can take a
                significant amount of time on a slow machine
                (several  seconds), but it is only done once
                at startup.  If ``none'' is  selected,  then
                TLS ciphersuites containing DSA/DH cannot be
                used.  If a file name  is  specified  (which
                must  be  an absolute path), then the primes
                are read from it.  It is recommended to gen-
                erate such a file using a command like this:

                                        openssl dhparam -out /etc/mail/dhparams.pem 2048

                If  the file is not readable or contains un-
                usable data, the default ``i'' is  used  in-
                stead.

      DaemonPortOptions=options
                [O]  Set server SMTP options.  Each instance
                of DaemonPortOptions leads to an  additional
                incoming  socket.  The options are key=value
                pairs.  Known keys are:

                    Name      User-definable name for the daemon (defaults to "Daemon#")
                    Port      Name/number of listening port (defaults to "smtp")
                    Addr      Address mask (defaults INADDR_ANY)
                    Family    Address family (defaults to INET)
                    InputMailFiltersList of input mail filters for the daemon
                    Listen    Size of listen queue (defaults to 10)
                    Modifier  Options (flags) for the daemon
                    SndBufSizeSize of TCP send buffer
                    RcvBufSizeSize of TCP receive buffer
                    children  maximum number of children per daemon, see MaxDaemonChildren.
                    DeliveryModeDelivery mode per daemon, see DeliveryMode.
                    refuseLA  RefuseLA per daemon
                    delayLA   DelayLA per daemon
                    queueLA   QueueLA per daemon

                The Name key is used for error messages  and
                logging.   The Address mask may be a numeric
                address in IPv4 dot notation or  IPv6  colon
                notation,  or a network name, or a path to a
                local socket.  Note that if a  network  name
                is  specified, only the first IP address re-
                turned for it will be used.  This may  cause
                indeterminate  behavior  for  network  names
                that resolve to multiple addresses.   There-
                fore, use of an address is recommended.  The
                Family key defaults to  INET  (IPv4).   IPv6










Sendmail Installation and Operation Guide         SMM:08-105


                users  who  wish to also accept IPv6 connec-
                tions  should  add  additional  Family=inet6
                DaemonPortOptions   lines.    For   a  local
                socket,  use  Family=local  or  Family=unix.
                The  InputMailFilters  key overrides the de-
                fault list of input mail filters  listed  in
                the  InputMailFilters  option.   If multiple
                input mail filters are required,  they  must
                be  separated  by  semicolons  (not commas).
                Modifier can be a sequence (without any  de-
                limiters) of the following characters:

                    a         always require authentication
                    b         bind to interface through which mail has been received
                    c         perform hostname canonification (.cf)
                    f         require fully qualified hostname (.cf)
                    s         Run smtps (SMTP over SSL) instead of smtp
                    u         allow unqualified addresses (.cf)
                    A         disable AUTH (overrides 'a' modifier)
                    C         don't perform hostname canonification
                    E         disallow ETRN (see RFC 2476)
                    O         optional; if opening the socket fails ignore it
                    S         don't offer STARTTLS

                That  is,  one way to specify a message sub-
                mission agent (MSA) that always requires au-
                thentication is:

                    O DaemonPortOptions=Name=MSA, Port=587, M=Ea

                The  modifiers  that are marked with "(.cf)"
                have only effect in the standard  configura-
                tion  file,  in which they are available via
                ${daemon_flags}.  Notice:  Do  not  use  the
                ``a''  modifier  on a public accessible MTA!
                It should only be used for a MSA that is ac-
                cessed  by authorized users for initial mail
                submission.  Users must authenticate to  use
                a  MSA which has this option turned on.  The
                flags ``c'' and ``C'' can change the default
                for  hostname  canonification  in  the send-
                mail.cf file.  See the  relevant  documenta-
                tion  for FEATURE(nocanonify).  The modifier
                ``f''  disallows  addresses  of   the   form
                user@host  unless  they  are  submitted  di-
                rectly.  The flag ``u''  allows  unqualified
                sender addresses, i.e., those without @host.
                ``b'' forces sendmail to bind to the  inter-
                face  through  which the e-mail has been re-
                ceived for the outgoing  connection.   WARN-
                ING:  Use ``b'' only if outgoing mail can be
                routed through the incoming connection's in-
                terface  to  its  destination. No attempt is










SMM:08-106         Sendmail Installation and Operation Guide


                made to catch problems due to a  misconfigu-
                ration  of  this  parameter, use it only for
                virtual hosting where each virtual interface
                can  connect  to  every  possible  location.
                This will also  override  possible  settings
                via  ClientPortOptions.  Note, sendmail will
                listen on a new socket for each occurence of
                the DaemonPortOptions option in a configura-
                tion file.  The modifier ``O'' causes  send-
                mail  to  ignore  a  socket  if  it can't be
                opened.  This applies to failures  from  the
                socket(2) and bind(2) calls.

      DefaultAuthInfo
                [no  short  name] Filename that contains de-
                fault authentication information for  outgo-
                ing  connections. This file must contain the
                user id, the authorization id, the  password
                (plain  text),  the  realm  and  the list of
                mechanisms to use on separate lines and must
                be  readable  by  root (or the trusted user)
                only.  If no realm is specified, $j is used.
                If  no  mechanisms  are  specified, the list
                given by AuthMechanisms  is  used.   Notice:
                this  option  is  deprecated and will be re-
                moved  in  future  versions.   Moreover,  it
                doesn't work for the MSP since it can't read
                the file (the file must not be  group/world-
                readable  otherwise sendmail will complain).
                Use the authinfo ruleset instead which  pro-
                vides  more  control  over  the usage of the
                data anyway.

      DefaultCharSet=charset
                [no short name]  When  a  message  that  has
                8-bit  characters  but is not in MIME format
                is converted to MIME (see  the  EightBitMode
                option)  a character set must be included in
                the Content-Type:  header.   This  character
                set  is normally set from the Charset= field
                of the mailer descriptor.  If  that  is  not
                set,  the  value of this option is used.  If
                this option  is  not  set,  the  value  "un-
                known-8bit" is used.

      DataFileBufferSize=threshold
                [no short name] Set the threshold, in bytes,
                before a memory-based queue  data  file  be-
                comes   disk-based.   The  default  is  4096
                bytes.

      DeadLetterDrop=file
                [no short name] Defines the location of  the










Sendmail Installation and Operation Guide         SMM:08-107


                system-wide dead.letter file, formerly hard-
                coded to /usr/tmp/dead.letter.  If this  op-
                tion is not set (the default), sendmail will
                not  attempt  to  save  to   a   system-wide
                dead.letter  file  in  the  event  it cannot
                bounce the mail to the user  or  postmaster.
                Instead,  it  will  rename the qf file as it
                has in the past when  the  dead.letter  file
                could not be opened.

      DefaultUser=user:group
                [u]  Set  the  default userid for mailers to
                user:group.  If group is omitted and user is
                a  user  name  (as opposed to a numeric user
                id)  the  default  group   listed   in   the
                /etc/passwd  file  for  that user is used as
                the default group.  Both user and group  may
                be  numeric.   Mailers without the S flag in
                the mailer definition will run as this user.
                Defaults  to  1:1.   The  value  can also be
                given as a symbolic user name.[19]

      DelayLA=LA
                [no short name] When the system load average
                exceeds LA, sendmail will sleep for one sec-
                ond on most SMTP commands and before accept-
                ing connections.

      DeliverByMin=time
                [0] Set minimum time  for  Deliver  By  SMTP
                Service Extension (RFC 2852).  If 0, no time
                is listed, if less than 0, the extension  is
                not offered, if greater than 0, it is listed
                as minimum time for the EHLO keyword  DELIV-
                ERBY.

      DeliveryMode=x
                [d] Deliver in mode x.  Legal modes are:

                    i   Deliver interactively (synchronously)
                    b   Deliver in background (asynchronously)
                    q   Just queue the message (deliver during queue run)
                    d   Defer delivery and all map lookups (deliver during queue run)

                Defaults to ``b'' if no option is specified,
                ``i'' if it is specified but given no  argu-
                ment   (i.e.,   ``Od''   is   equivalent  to
                ``Odi'').  The -v  command  line  flag  sets
____________________
   [19]The old g option has been combined into the  Default-
User option.












SMM:08-108         Sendmail Installation and Operation Guide


                this  to  i.   Note:  for  internal reasons,
                ``i'' does not work if a milter  is  enabled
                which  can  reject or delete recipients.  In
                that case the mode will be changed to ``b''.

      DialDelay=sleeptime
                [no short name] Dial-on-demand network  con-
                nections can see timeouts if a connection is
                opened before the call is set up.   If  this
                is set to an interval and a connection times
                out on the first connection being  attempted
                sendmail  will sleep for this amount of time
                and try again.  This should give your system
                time  to  establish  the  connection to your
                service provider.  Units default to seconds,
                so  "DialDelay=5"  uses a five second delay.
                Defaults to zero  (no  retry).   This  delay
                only  applies  to  mailers  which have the Z
                flag set.

      DirectSubmissionModifiers=modifiers
                Defines ${daemon_flags} for direct  (command
                line)   submissions.   If  not  set,  ${dae-
                mon_flags} is either "CC f" if the option -G
                is  used or "c u" otherwise.  Note that only
                the the "CC", "c", "f", and  "u"  flags  are
                checked.

      DontBlameSendmail=option,option,...
                [no  short  name] In order to avoid possible
                cracking  attempts  caused  by  world-   and
                group-writable  files and directories, send-
                mail does  paranoid  checking  when  opening
                most of its support files.  If for some rea-
                son you absolutely must run with, for  exam-
                ple,  a  group-writable /etc directory, then
                you will have to turn off this checking  (at
                the cost of making your system more vulnera-
                ble to attack).  The possible arguments have
                been  described  earlier.   The  details  of
                these flags are  described  above.   Use  of
                this option is not recommended.

      DontExpandCnames
                [no  short  name] The standards say that all
                host addresses used in a mail  message  must
                be  fully  canonical.   For example, if your
                host is named "Cruft.Foo.ORG" and  also  has
                an  alias  of "FTP.Foo.ORG", the former name
                must be used at all times.  This is enforced
                during  host  name canonification ($[ ... $]
                lookups).  If this option is set, the proto-
                cols  are  ignored  and the "wrong" thing is










Sendmail Installation and Operation Guide         SMM:08-109


                done.  However, the IETF  is  moving  toward
                changing  this standard, so the behavior may
                become acceptable.  Please note  that  hosts
                downstream  may still rewrite the address to
                be the true canonical name however.

      DontInitGroups
                [no short name] If set, sendmail will  avoid
                using  the  initgroups(3)  call.  If you are
                running NIS, this causes a  sequential  scan
                of  the  groups.byname  map, which can cause
                your NIS server to be badly overloaded in  a
                large  domain.  The cost of this is that the
                only group found for  users  will  be  their
                primary  group  (the  one  in  the  password
                file), which will make file  access  permis-
                sions somewhat more restrictive.  Has no ef-
                fect on systems that don't have group lists.

      DontProbeInterfaces
                [no short name] Sendmail normally finds  the
                names  of  all interfaces active on your ma-
                chine when it starts up and adds their  name
                to  the $=w class of known host aliases.  If
                you have a large number  of  virtual  inter-
                faces  or  if  your  DNS inverse lookups are
                slow this can be time consuming.   This  op-
                tion  turns  off that probing.  However, you
                will need to be certain to include all vari-
                ant  names  in  the  $=w class by some other
                mechanism.  If set to loopback, loopback in-
                terfaces (e.g., lo0) will not be probed.

      DontPruneRoutes
                [R]  Normally,  sendmail  tries to eliminate
                any unnecessary explicit routes when sending
                an error message (as discussed in RFC 1123 S
                5.2.6).  For example, when sending an  error
                message to

                    <@known1,@known2,@known3:user@unknown>

                sendmail      will     strip     off     the
                "@known1,@known2" in order to make the route
                as  direct  as  possible.  However, if the R
                option is set, this will  be  disabled,  and
                the  mail  will be sent to the first address
                in the route, even if  later  addresses  are
                known.  This may be useful if you are caught
                behind a firewall.

      DoubleBounceAddress=error-address
                [no short name]  If  an  error  occurs  when










SMM:08-110         Sendmail Installation and Operation Guide


                sending an error message, send the error re-
                port (termed a "double bounce" because it is
                an error "bounce" that occurs when trying to
                send another error "bounce")  to  the  indi-
                cated  address.   The  address  is macro ex-
                panded at the time of delivery.  If not set,
                defaults  to  "postmaster".   If  set  to an
                empty string, double bounces are dropped.

      EightBitMode=action
                [8] Set handling of eight-bit  data.   There
                are  two  kinds  of eight-bit data: that de-
                clared as such using the BODY=8BITMIME ESMTP
                declaration  or  the -B8BITMIME command line
                flag, and undeclared 8-bit  data,  that  is,
                input  that  just  happens to be eight bits.
                There are three basic  operations  that  can
                happen:  undeclared  8-bit data can be auto-
                matically converted to 8BITMIME,  undeclared
                8-bit  data can be passed as-is without con-
                version to MIME (``just send 8''),  and  de-
                clared 8-bit data can be converted to 7-bits
                for transmission to a  non-8BITMIME  mailer.
                The possible actions are:

                      s Reject undeclared 8-bit data (``strict'')
                      m Convert undeclared 8-bit data to MIME (``mime'')
                      p Pass undeclared 8-bit data (``pass'')

                In all cases properly declared 8BITMIME data
                will be converted to 7BIT as needed.

      ErrorHeader=file-or-message
                [E] Prepend error messages  with  the  indi-
                cated  message.   If it begins with a slash,
                it is assumed to be the pathname of  a  file
                containing  a  message  (this  is the recom-
                mended setting).  Otherwise, it is a literal
                message.   The  error file might contain the
                name, email address, and/or phone number  of
                a local postmaster who could provide assist-
                ance to end users.  If the option is missing
                or  null,  or  if it names a file which does
                not exist or which is not readable, no  mes-
                sage is printed.

      ErrorMode=x
                [e]  Dispose  of  errors  using mode x.  The
                values for x are:














Sendmail Installation and Operation Guide         SMM:08-111


                    p   Print error messages (default)
                    q   No messages, just give exit status
                    m   Mail back errors
                    w   Write back errors (mail if user not logged in)
                    e   Mail back errors (when applicable) and give zero exit stat always

                Note that the last mode, "e", is for Berknet
                error  processing  and should not be used in
                normal circumstances.  Note, too, that  mode
                "q",  only  applies to errors recognized be-
                fore sendmail forks for background delivery.

      FallbackMXhost=fallbackhost
                [V] If specified, the fallbackhost acts like
                a  very  low  priority MX on every host.  MX
                records will be looked up for this host, un-
                less the name is surrounded by square brack-
                ets.  This is intended to be used  by  sites
                with  poor  network  connectivity.  Messages
                which are undeliverable due to temporary ad-
                dress  failures  (e.g., DNS failure) also go
                to the FallbackMXhost.

      FallBackSmartHost=hostname
                If specified, the FallBackSmartHost will  be
                used  in  a last-ditch effort for each host.
                This is intended to be used  by  sites  with
                "fake  internal  DNS", e.g., a company whose
                DNS accurately  reflects  the  world  inside
                that company's domain but not outside.

      FastSplit [no  short  name]  If set to a value greater
                than zero (the  default  is  one),  it  sup-
                presses  the  MX  lookups  on addresses when
                they are initially  sorted,  i.e.,  for  the
                first  delivery  attempt.   This usually re-
                sults in faster  envelope  splitting  unless
                the  MX  records  are readily available in a
                local DNS cache.  To enforce initial sorting
                based  on  MX records set FastSplit to zero.
                If the mail is submitted directly  from  the
                command line, then the value also limits the
                number  of  processes  to  deliver  the  en-
                velopes;  if more envelopes are created they
                are only queued up and must be taken care of
                by  a  queue run.  Since the default submis-
                sion method is via SMTP (either from  a  MUA
                or  via  the MSP), the value of FastSplit is
                seldom used to limit the number of processes
                to deliver the envelopes.

      ForkEachJob
                [Y]  If  set,  deliver  each job that is run










SMM:08-112         Sendmail Installation and Operation Guide


                from the queue in a separate process.

      ForwardPath=path
                [J] Set the path for  searching  for  users'
                .forward  files.   The  default is "$z/.for-
                ward".  Some sites that use the  automounter
                may  prefer  to  change  this  to "/var/for-
                ward/$u" to search a file with the same name
                as  the  user in a system directory.  It can
                also be set to a sequence of paths separated
                by  colons; sendmail stops at the first file
                it can successfully and  safely  open.   For
                example,  "/var/forward/$u:$z/.forward" will
                search first  in  /var/forward/username  and
                then  in ~username/.forward (but only if the
                first file does not exist).

      HeloName=name
                [no short name] Set the name to be used  for
                HELO/EHLO (instead of $j).

      HoldExpensive
                [c] If an outgoing mailer is marked as being
                expensive, don't connect immediately.

      HostsFile=path
                [no short name] The path to the hosts  data-
                base, normally "/etc/hosts".  This option is
                only consulted when sendmail is  canonifying
                addresses,  and then only when "files" is in
                the "hosts" service switch entry.   In  par-
                ticular,  this file is never used when look-
                ing up host addresses;  that  is  under  the
                control  of the system gethostbyname(3) rou-
                tine.

      HostStatusDirectory=path
                [no short name] The  location  of  the  long
                term host status information.  When set, in-
                formation about the status of  hosts  (e.g.,
                host down or not accepting connections) will
                be shared between  all  sendmail  processes;
                normally,  this  information  is  only  held
                within a single queue run.  This option  re-
                quires  a  connection cache of at least 1 to
                function.  If the option begins with a lead-
                ing  `/', it is an absolute pathname; other-
                wise, it is relative to the mail  queue  di-
                rectory.  A suggested value for sites desir-
                ing persistent host  status  is  ".hoststat"
                (i.e.,  a  subdirectory  of the queue direc-
                tory).











Sendmail Installation and Operation Guide         SMM:08-113


      IgnoreDots
                [i] Ignore dots in incoming messages.   This
                is always disabled (that is, dots are always
                accepted) when reading SMTP mail.

      InputMailFilters=name,name,...
                A comma separated list of filters which  de-
                termines  which  filters (see the "X -- Mail
                Filter (Milter)  Definitions"  section)  and
                the  invocation  sequence  are contacted for
                incoming SMTP messages.  If none are set, no
                filters will be contacted.

      LDAPDefaultSpec=spec
                [no  short name] Sets a default map specifi-
                cation for LDAP maps.  The value should only
                contain  LDAP  specific settings such as "-h
                host -p port -d bindDN".  The settings  will
                be  used  for all LDAP maps unless the indi-
                vidual map specification  overrides  a  set-
                ting.   This option should be set before any
                LDAP maps are defined.

      LogLevel=n
                [L] Set the log level to n.  Defaults to 9.

      Mxvalue   [no long version] Set the macro x to  value.
                This  is intended only for use from the com-
                mand line.  The -M flag is preferred.

      MailboxDatabase
                [no short name] Type of lookup to  find  in-
                formation about local mailboxes, defaults to
                ``pw'' which uses getpwnam.  Other types can
                be  introduced  by adding them to the source
                code, see libsm/mbdb.c for details.

      UseMSP    [no short name] Use as mail submission  pro-
                gram, i.e., allow group writable queue files
                if the group is the same as that of  a  set-
                group-ID  sendmail  binary.   See  the  file
                sendmail/SECURITY in the  distribution  tar-
                ball.

      MatchGECOS
                [G] Allow fuzzy matching on the GECOS field.
                If this flag is set, and the usual user name
                lookups  fail  (that  is,  there is no alias
                with this name and a  getpwnam  fails),  se-
                quentially  search  the  password file for a
                matching entry in  the  GECOS  field.   This
                also  requires  that MATCHGECOS be turned on
                during  compilation.   This  option  is  not










SMM:08-114         Sendmail Installation and Operation Guide


                recommended.

      MaxAliasRecursion=N
                [no  short  name] The maximum depth of alias
                recursion (default: 10).

      MaxDaemonChildren=N
                [no short name] If set, sendmail will refuse
                connections when it has more than N children
                processing incoming mail or automatic  queue
                runs.   This  does  not  limit the number of
                outgoing connections.  If the default Deliv-
                eryMode  (background) is used, then sendmail
                may create an  almost  unlimited  number  of
                children  (depending on the number of trans-
                actions and the relative execution times  of
                mail  receiption and mail delivery).  If the
                limit should be enforced, then  a  Delivery-
                Mode other than background must be used.  If
                not set, there is no limit to the number  of
                children -- that is, the system load average
                controls this.

      MaxHeadersLength=N
                [no short name] The maximum  length  of  the
                sum  of  all  headers.   This can be used to
                prevent a denial of service attack.  The de-
                fault is no limit.

      MaxHopCount=N
                [h]  The  maximum  hop count.  Messages that
                have been processed more than  N  times  are
                assumed  to  be  in a loop and are rejected.
                Defaults to 25.

      MaxMessageSize=N
                [no short name] Specify the maximum  message
                size  to be advertised in the ESMTP EHLO re-
                sponse.  Messages larger than this  will  be
                rejected.   If  set  to a value greater than
                zero, that value will be listed in the  SIZE
                response,  otherwise  SIZE  is advertised in
                the ESMTP EHLO response without a parameter.

      MaxMimeHeaderLength=N[/M]
                [no short name] Sets the maximum  length  of
                certain  MIME header field values to N char-
                acters.  These MIME header fields are deter-
                mined by being a member of class {checkMIME-
                TextHeaders}, which currently contains  only
                the header Content-Description.  For some of
                these headers  which  take  parameters,  the
                maximum length of each parameter is set to M










Sendmail Installation and Operation Guide         SMM:08-115


                if specified.  If /M is not  specified,  one
                half  of  N will be used.  By default, these
                values are 2048 and 1024, respectively.   To
                allow any length, a value of 0 can be speci-
                fied.

      MaxNOOPCommands=N
                Override the default of MAXNOOPCOMMANDS  for
                the  number of useless commands, see Section
                "Measures  against  Denial  of  Service  At-
                tacks".

      MaxQueueChildren=N
                [no  short  name]  When set, this limits the
                number of concurrent queue runner  processes
                to  N.   This helps to control the amount of
                system resources used  when  processing  the
                queue.  When there are multiple queue groups
                defined and the total number of  queue  run-
                ners  for  these  queue  groups would exceed
                MaxQueueChildren then the queue groups  will
                not all run concurrently. That is, some por-
                tion of the queue groups  will  run  concur-
                rently  such  that MaxQueueChildren will not
                be  exceeded,  while  the  remaining   queue
                groups will be run later (in round robin or-
                der). See also  MaxRunnersPerQueue  and  the
                section  Queue  Group  Declaration.  Notice:
                sendmail does  not  count  individual  queue
                runners, but only sets of processes that act
                on a workgroup.  Hence the actual number  of
                queue  runners  may  be lower than the limit
                imposed by MaxQueueChildren.  This  discrep-
                ancy can be large if some queue runners have
                to wait for a slow server and if  short  in-
                tervals are used.

      MaxQueueRunSize=N
                [no  short  name] The maximum number of jobs
                that will be processed  in  a  single  queue
                run.   If  not set, there is no limit on the
                size.  If you have very large  queues  or  a
                very  short queue run interval this could be
                unstable.  However, since the first  N  jobs
                in  queue  directory  order  are run (rather
                than  the  N  highest  priority  jobs)  this
                should  be  set as high as possible to avoid
                "losing" jobs that happen to  fall  late  in
                the queue directory.  Note: this option also
                restricts the number of entries  printed  by
                mailq.   That  is, if MaxQueueRunSize is set
                to a value N larger than zero, then  only  N
                entries are printed per queue group.










SMM:08-116         Sendmail Installation and Operation Guide


      MaxRecipientsPerMessage=N
                [no short name] The maximum number of recip-
                ients that will be accepted per  message  in
                an SMTP transaction.  Note: setting this too
                low can interfere  with  sending  mail  from
                MUAs  that  use SMTP for initial submission.
                If not set, there is no limit on the  number
                of recipients per envelope.

      MaxRunnersPerQueue=N
                [no  short name] This sets the default maxi-
                mum  number  of  queue  runners  for   queue
                groups.   Up to N queue runners will work in
                parallel on a queue group's messages.   This
                is  useful where the processing of a message
                in the queue might delay the  processing  of
                subsequent messages. Such a delay may be the
                result of non-erroneous situations such as a
                low bandwidth connection.  May be overridden
                on a per queue group basis  by  setting  the
                Runners  option; see the section Queue Group
                Declaration.  The default is 1 when not set.

      MeToo     [m] Send to me too, even if I am in an alias
                expansion.   This  option  is deprecated and
                will be removed from a future version.

      Milter    [no short  name]  This  option  has  several
                sub(sub)options.   The  names  of the subop-
                tions are separated by dots.  At  the  first
                level the following options are available:

                    LogLevel   Log level for input mail filter actions, defaults to LogLevel.
                    macros     Specifies list of macro to transmit to filters.
                               See list below.

                The ``macros'' option has the following sub-
                options which specify the list of  macro  to
                transmit  to  milters  after a certain event
                occurred.

                    connect   After session connection start
                    helo      After EHLO/HELO command
                    envfrom   After MAIL From command
                    envrcpt   After RCPT To command
                    data      After DATA command.
                    eoh       After DATA command and header
                    eom       After DATA command and terminating ``.''

                By default the lists of  macros  are  empty.
                Example:












Sendmail Installation and Operation Guide         SMM:08-117


                    O Milter.LogLevel=12
                    O Milter.macros.connect=j, _, {daemon_name}


      MinFreeBlocks=N
                [b]  Insist on at least N blocks free on the
                filesystem that holds the queue files before
                accepting  email  via SMTP.  If there is in-
                sufficient space sendmail gives  a  452  re-
                sponse  to  the  MAIL command.  This invites
                the sender to try again later.

      MaxQueueAge=age
                [no short name] If this is set  to  a  value
                greater than zero, entries in the queue will
                be retried during a queue run  only  if  the
                individual retry time has been reached which
                is doubled for each  attempt.   The  maximum
                retry  time  is  limited  by  the  specified
                value.

      MinQueueAge=age
                [no short name]  Don't  process  any  queued
                jobs  that  have been in the queue less than
                the indicated time interval.   This  is  in-
                tended to allow you to get responsiveness by
                processing the queue fairly frequently with-
                out thrashing your system by trying jobs too
                often.   The  default  units  are   minutes.
                Note:  This option is ignored for queue runs
                that select a subset  of  the  queue,  i.e.,
                "-q[!][I|R|S|Q][string]"

      MustQuoteChars=s
                [no  short name] Sets the list of characters
                that must be quoted if used in a  full  name
                that  is  in  the  phrase part of a ``phrase
                <address>'' syntax.  The default is  ``'.''.
                The   characters  ``@,;:\()[]''  are  always
                added to this list.

      NiceQueueRun
                [no short name] The priority of  queue  run-
                ners  (nice(3)).  This value must be greater
                or equal zero.

      NoRecipientAction
                [no short name] The action to take when  you
                receive  a message that has no valid recipi-
                ent headers (To:, Cc:, Bcc:, or  Apparently-
                To:  --  the last included for back compati-
                bility with old sendmails).  It can be  None
                to  pass  the  message  on unmodified, which










SMM:08-118         Sendmail Installation and Operation Guide


                violates the protocol, Add-To to add  a  To:
                header  with  any  recipients it can find in
                the envelope (which might expose Bcc: recip-
                ients),  Add-Apparently-To  to add an Appar-
                ently-To: header (this is only for back-com-
                patibility  and  is  officially deprecated),
                Add-To-Undisclosed  to  add  a  header  "To:
                undisclosed-recipients:;" to make the header
                legal without disclosing anything,  or  Add-
                Bcc to add an empty Bcc: header.

      OldStyleHeaders
                [o]  Assume  that  the headers may be in old
                format, i.e., spaces  delimit  names.   This
                actually  turns on an adaptive algorithm: if
                any  recipient  address  contains  a  comma,
                parenthesis,  or  angle  bracket, it will be
                assumed that commas already exist.  If  this
                flag  is  not on, only commas delimit names.
                Headers are always output  with  commas  be-
                tween the names.  Defaults to off.

      OperatorChars=charlist
                [$o  macro]  The list of characters that are
                considered to be "operators", that is, char-
                acters  that  delimit  tokens.  All operator
                characters are  tokens  by  themselves;  se-
                quences  of non-operator characters are also
                tokens.  White space characters separate to-
                kens  but  are  not tokens themselves -- for
                example, "AAA.BBB"  has  three  tokens,  but
                "AAA  BBB"  has  two.  If not set, Operator-
                Chars defaults to ".:@[]"; additionally, the
                characters  "()<>,;"  are  always operators.
                Note that OperatorChars must be set  in  the
                configuration file before any rulesets.

      PidFile=filename
                [no  short  name]  Filename of the pid file.
                (default is _PATH_SENDMAILPID).   The  file-
                name  is macro-expanded before it is opened,
                and unlinked when sendmail exits.

      PostmasterCopy=postmaster
                [P] If set, copies of error messages will be
                sent  to  the  named  postmaster.   Only the
                header of the failed message is  sent.   Er-
                rors resulting from messages with a negative
                precedence will not be sent.  Since most er-
                rors are user problems, this is probably not
                a good idea on  large  sites,  and  arguably
                contains  all  sorts  of privacy violations,
                but it seems  to  be  popular  with  certain










Sendmail Installation and Operation Guide         SMM:08-119


                operating  systems  vendors.  The address is
                macro expanded at the time of delivery.  De-
                faults to no postmaster copies.

      PrivacyOptions=opt,opt,...
                [p] Set the privacy options.  ``Privacy'' is
                really a misnomer; many of these are just  a
                way  of  insisting  on stricter adherence to
                the SMTP protocol.  The options can  be  se-
                lected from:

                    public              Allow open access
                    needmailhelo        Insist on HELO or EHLO command before MAIL
                    needexpnhelo        Insist on HELO or EHLO command before EXPN
                    noexpn              Disallow EXPN entirely, implies noverb.
                    needvrfyhelo        Insist on HELO or EHLO command before VRFY
                    novrfy              Disallow VRFY entirely
                    noetrn              Disallow ETRN entirely
                    noverb              Disallow VERB entirely
                    restrictmailq       Restrict mailq command
                    restrictqrun        Restrict -q command line flag
                    restrictexpand      Restrict -bv and -v command line flags
                    noreceipts          Don't return success DSNs[20]
                    nobodyreturn        Don't return the body of a message with DSNs
                    goaway              Disallow essentially all SMTP status queries
                    authwarnings        Put X-Authentication-Warning: headers in messages
                                        and log warnings
                    noactualrecipient   Don't put X-Actual-Recipient lines in DSNs
                                        which reveal the actual account that addresses map to.

                The "goaway" pseudo-flag sets all flags  ex-
                cept   "noreceipts",  "restrictmailq",  "re-
                strictqrun", "restrictexpand", "noetrn", and
                "nobodyreturn".   If  mailq  is  restricted,
                only people in the same group as  the  queue
                directory  can  print  the  queue.  If queue
                runs are restricted, only root and the owner
                of  the  queue  directory can run the queue.
                The "restrictexpand"  pseudo-flag  instructs
                sendmail to drop privileges when the -bv op-
                tion is given by users who are neither  root
                nor  the  TrustedUser  so  users cannot read
                private  aliases,  forwards,  or   :include:
                files.  It will add the "NonRootSafeAddr" to
                the "DontBlameSendmail"  option  to  prevent
                misleading unsafe address warnings.  It also
                overrides the -v (verbose) command line  op-
                tion   to   prevent   information   leakage.
____________________
   [20]N.B.:  the  noreceipts flag turns off support for RFC
1891 (Delivery Status Notification).












SMM:08-120         Sendmail Installation and Operation Guide


                Authentication Warnings add  warnings  about
                various  conditions  that  may  indicate at-
                tempts to spoof the mail system, such as us-
                ing a non-standard queue directory.

      ProcessTitlePrefix=string
                [no  short  name]  Prefix  the process title
                shown on 'ps'  listings  with  string.   The
                string will be macro processed.

      QueueDirectory=dir
                [Q]  The  QueueDirectory  option  serves two
                purposes.  First, it specifies the directory
                or  set of directories that comprise the de-
                fault queue group.  Second, it specifies the
                directory  D  which  is  the ancestor of all
                queue directories, and which  sendmail  uses
                as  its  current  working  directory.   When
                sendmail dumps  core,  it  leaves  its  core
                files  in  D.   There are two cases.  If dir
                ends     with     an      asterisk      (eg,
                /var/spool/mqueue/qd*),  then all of the di-
                rectories or symbolic links  to  directories
                beginning  with  `qd'  in  /var/spool/mqueue
                will be used as queue directories of the de-
                fault  queue  group,  and  /var/spool/mqueue
                will be used as  the  working  directory  D.
                Otherwise,  dir  must name a directory (usu-
                ally /var/spool/mqueue): the  default  queue
                group consists of the single queue directory
                dir, and the working directory D is  set  to
                dir.   To  define additional groups of queue
                directories, use the configuration file  `Q'
                command.   Do not change the queue directory
                structure while sendmail is running.

      QueueFactor=factor
                [q] Use factor as the multiplier in the  map
                function  to  decide  when  to just queue up
                jobs rather than run them.   This  value  is
                divided  by  the difference between the cur-
                rent load average and the load average limit
                (QueueLA  option)  to  determine the maximum
                message priority that  will  be  sent.   De-
                faults to 600000.

      QueueLA=LA
                [x]  When the system load average exceeds LA
                and the QueueFactor (q)  option  divided  by
                the  difference  in the current load average
                and the QueueLA option plus one is less than
                the priority of the message, just queue mes-
                sages  (i.e.,  don't  try  to  send   them).










Sendmail Installation and Operation Guide         SMM:08-121


                Defaults  to  8  multiplied by the number of
                processors online on the system (if that can
                be determined).

      QueueFileMode=mode
                [no  short  name]  Default  permissions  for
                queue files (octal).  If not  set,  sendmail
                uses  0600 unless its real and effective uid
                are different in which case it uses 0644.

      QueueSortOrder=algorithm
                [no short name] Sets the algorithm used  for
                sorting the queue.  Only the first character
                of the value  is  used.   Legal  values  are
                "host"  (to  order  by the name of the first
                host name of the  first  recipient),  "file-
                name"  (to  order  by  the name of the queue
                file name), "time" (to order by the  submis-
                sion/creation time), "random" (to order ran-
                domly), "modification" (to order by the mod-
                ification time of the qf file (older entries
                first)), "none" (to not order), and  "prior-
                ity"  (to  order by message priority).  Host
                ordering makes better use of the  connection
                cache,  but may tend to process low priority
                messages that go to a single host over  high
                priority  messages that go to several hosts;
                it probably shouldn't be used on  slow  net-
                work  links.  Filename and modification time
                ordering saves the overhead of  reading  all
                of  the  queued  items  before  starting the
                queue run.  Creation (submission)  time  or-
                dering is almost always a bad idea, since it
                allows large, bulk mail  to  go  out  before
                smaller,  personal mail, but may have appli-
                cability on some hosts with very  fast  con-
                nections.  Random is useful if several queue
                runners are started by  hand  which  try  to
                drain  the  same  queue  since odds are they
                will be working on different  parts  of  the
                queue  at  the same time.  Priority ordering
                is the default.

      QueueTimeout=timeout
                [T]  A  synonym  for  "Timeout.queuereturn".
                Use  that form instead of the "QueueTimeout"
                form.

      RandFile  [no short name] Name of file containing ran-
                dom  data  or the name of the UNIX socket if
                EGD is used.  A (required) prefix "egd:"  or
                "file:"  specifies  the  type.  STARTTLS re-
                quires this filename  if  the  compile  flag










SMM:08-122         Sendmail Installation and Operation Guide


                HASURANDOMDEV   is   not   set   (see  send-
                mail/README).

      ResolverOptions=options
                [I] Set resolver options.  Values can be set
                using  +flag  and  cleared  using -flag; the
                flags can  be  "debug",  "aaonly",  "usevc",
                "primary",  "igntc",  "recurse", "defnames",
                "stayopen", "use_inet6", or  "dnsrch".   The
                string  "HasWildcardMX"  (without  a + or -)
                can  be  specified  to  turn  off   matching
                against MX records when doing name canonifi-
                cations.  The string  "WorkAroundBrokenAAAA"
                (without  a + or -) can be specified to work
                around some broken nameservers which  return
                SERVFAIL  (a  temporary  failure)  on T_AAAA
                (IPv6) lookups.  Notice: it might be  neces-
                sary  to apply the same (or similar) options
                to submit.cf too.

      RequiresDirfsync
                [no short name] This option can be  used  to
                override   the   compile   time   flag   RE-
                QUIRES_DIR_FSYNC at runtime by setting it to
                false.  If the compile time flag is not set,
                the option is ignored.  The  flag  turns  on
                support  for  file  systems  that require to
                call fsync() for a directory  if  the  meta-
                data in it has been changed.  This should be
                turned on at least  for  older  versions  of
                ReiserFS;  it  is  enabled  by  default  for
                Linux.  According to some  information  this
                flag is not needed anymore for kernel 2.4.16
                and newer.

      RrtImpliesDsn
                [R] If this option  is  set,  a  "Return-Re-
                ceipt-To:"  header  causes  the request of a
                DSN, which is sent to the envelope sender as
                required  by  RFC  1891,  not to the address
                given in the header.

      RunAsUser=user
                [no short name] The user parameter may be  a
                user  name  (looked  up in /etc/passwd) or a
                numeric  user  id;  either  form  can   have
                ":group"  attached  (where  group can be nu-
                meric or symbolic).  If set  to  a  non-zero
                (non-root)  value,  sendmail  will change to














Sendmail Installation and Operation Guide         SMM:08-123


                this  user  id  shortly  after  startup[21].
                This  avoids  a  certain  class  of security
                problems.   However,  this  means  that  all
                ".forward"  and  ":include:"  files  must be
                readable by the indicated user and all files
                to be written must be writable by user Also,
                all file  and  program  deliveries  will  be
                marked  unsafe  unless the option DontBlame-
                Sendmail=NonRootSafeAddr is  set,  in  which
                case  the delivery will be done as user.  It
                is also incompatible with the  SafeFileEnvi-
                ronment  option.  In other words, it may not
                actually add much to security on an  average
                system,  and  may in fact detract from secu-
                rity (because other file permissions must be
                loosened).   However, it should be useful on
                firewalls and other places where users don't
                have  accounts  and the aliases file is well
                constrained.

      RecipientFactor=fact
                [y] The indicated factor  is  added  to  the
                priority  (thus lowering the priority of the
                job) for each recipient,  i.e.,  this  value
                penalizes jobs with large numbers of recipi-
                ents.  Defaults to 30000.

      RefuseLA=LA
                [X] When the system load average exceeds LA,
                refuse  incoming SMTP connections.  Defaults
                to 12 multiplied by the number of processors
                online  on the system (if that can be deter-
                mined).

      RejectLogInterval=timeout
                [no short name] Log interval  when  refusing
                connections for this long (default: 3h).

      RetryFactor=fact
                [Z]  The factor is added to the priority ev-
                ery time a job  is  processed.   Thus,  each
                time  a  job is processed, its priority will
                be decreased by  the  indicated  value.   In
                most  environments  this should be positive,
                since hosts that are down are all too  often
                down for a long time.  Defaults to 90000.


____________________
   [21]When running as a daemon, it changes to this user af-
ter  accepting a connection but before reading any SMTP com-
mands.











SMM:08-124         Sendmail Installation and Operation Guide


      SafeFileEnvironment=dir
                [no short name] If this option is set, send-
                mail will do a chroot(2) call into the indi-
                cated   directory   before  doing  any  file
                writes.  If the file name specified  by  the
                user begins with dir, that partial path name
                will be stripped off before writing, so (for
                example) if the SafeFileEnvironment variable
                is  set   to   "/safe"   then   aliases   of
                "/safe/logs/file"  and "/logs/file" actually
                indicate the same  file.   Additionally,  if
                this  option is set, sendmail refuses to de-
                liver to symbolic links.

      SaveFromLine
                [f] Save  UNIX-style  "From"  lines  at  the
                front of headers.  Normally they are assumed
                redundant and discarded.

      SendMimeErrors
                [j] If set, send error messages in MIME for-
                mat (see RFC 2045 and RFC 1344 for details).
                If disabled, sendmail will  not  return  the
                DSN  keyword in response to an EHLO and will
                not do Delivery Status Notification process-
                ing as described in RFC 1891.

      ServerCertFile
                [no short name] File containing the certifi-
                cate of the server, i.e.,  this  certificate
                is  used  when sendmail acts as server (used
                for STARTTLS).

      ServerKeyFile
                [no short name] File containing the  private
                key  belonging  to  the  server  certificate
                (used for STARTTLS).

      ServerSSLOptions
                A space or comma separated list of  SSL  re-
                lated  options  for  the  server  side.  See
                SSL_CTX_set_options(3)  for  a   list;   the
                available  values depend on the OpenSSL ver-
                sion against which sendmail is compiled.  By
                default,  SSL_OP_ALL  -SSL_OP_TLSEXT_PADDING
                are used (if those options  are  available).
                Options  can  be  cleared by preceeding them
                with a minus sign.  It is also  possible  to
                specify numerical values, e.g., -0x0010.

      ServiceSwitchFile=filename
                [no  short name] If your host operating sys-
                tem has a service switch abstraction  (e.g.,










Sendmail Installation and Operation Guide         SMM:08-125


                /etc/nsswitch.conf     on     Solaris     or
                /etc/svc.conf on Ultrix and DEC OSF/1)  that
                service will be consulted and this option is
                ignored.  Otherwise, this is the name  of  a
                file  that provides the list of methods used
                to implement particular services.  The  syn-
                tax is a series of lines, each of which is a
                sequence of words.  The first  word  is  the
                service  name,  and following words are ser-
                vice types.  The services that sendmail con-
                sults  directly  are  "aliases" and "hosts."
                Service types can  be  "dns",  "nis",  "nis-
                plus",  or "files" (with the caveat that the
                appropriate support must be compiled in  be-
                fore  the  service  can  be referenced).  If
                ServiceSwitchFile is not specified,  it  de-
                faults to /etc/mail/service.switch.  If that
                file does not exist, the default switch is:

                    aliases             files
                    hosts               dns nis files

                The   default   file   is    "/etc/mail/ser-
                vice.switch".

      SevenBitInput
                [7]  Strip  input to seven bits for compati-
                bility with old systems.  This shouldn't  be
                necessary.

      SharedMemoryKey
                [no short name] Key to use for shared memory
                segment; if not set (or  0),  shared  memory
                will not be used.  If set to -1 sendmail can
                select  a  key  itself  provided  that  also
                SharedMemoryKeyFile  is  set.  Requires sup-
                port for shared memory to be  compiled  into
                sendmail.   If  this option is set, sendmail
                can share some data  between  different  in-
                stances.  For example, the number of entries
                in a queue directory or the available  space
                in  a file system.  This allows for more ef-
                ficient program execution,  since  only  one
                process  needs to update the data instead of
                each individual process gathering  the  data
                each time it is required.

      SharedMemoryKeyFile
                [no short name] If SharedMemoryKey is set to
                -1 then the  automatically  selected  shared
                memory  key  will be stored in the specified
                file.











SMM:08-126         Sendmail Installation and Operation Guide


      SingleLineFromHeader
                [no short name] If  set,  From:  lines  that
                have  embedded  newlines  are unwrapped onto
                one line.  This is to get around a botch  in
                Lotus  Notes  that  apparently cannot under-
                stand legally wrapped RFC 822 headers.

      SingleThreadDelivery
                [no short name] If  set,  a  client  machine
                will  never try to open two SMTP connections
                to a single server machine at the same time,
                even  in  different  processes.  That is, if
                another sendmail is already talking to  some
                host  a  new  sendmail will not open another
                connection.   This  property  is  of   mixed
                value; although this reduces the load on the
                other machine, it can cause mail to  be  de-
                layed  (for  example, if one sendmail is de-
                livering a  huge  message,  other  sendmails
                won't  be able to send even small messages).
                Also, it requires  another  file  descriptor
                (for  the  lock file) per connection, so you
                may have to reduce  the  ConnectionCacheSize
                option  to  avoid running out of per-process
                file descriptors.  Requires the  HostStatus-
                Directory option.

      SmtpGreetingMessage=message
                [$e macro] The message printed when the SMTP
                server starts up.  Defaults to "$j  Sendmail
                $v ready at $b".

      SoftBounce
                If set, issue temporary errors (4xy) instead
                of permanent errors (5xy).  This can be use-
                ful during testing of a new configuration to
                avoid erroneous bouncing of mails.

      StatusFile=file
                [S] Log  summary  statistics  in  the  named
                file.   If  no file name is specified, "sta-
                tistics" is used.  If not  set,  no  summary
                statistics  are  saved.   This file does not
                grow in size.  It can be printed  using  the
                mailstats(8) program.

      SuperSafe [s]  This  option can be set to True, False,
                Interactive, or PostMilter.  If set to True,
                sendmail  will  be  super-safe  when running
                things, i.e., always instantiate  the  queue
                file, even if you are going to attempt imme-
                diate delivery.  Sendmail  always  instanti-
                ates the queue file before returning control










Sendmail Installation and Operation Guide         SMM:08-127


                to the client under any circumstances.  This
                should  really  always  be set to True.  The
                Interactive value  has  been  introduced  in
                8.12 and can be used together with Delivery-
                Mode=i.  It skips some synchronization calls
                which  are  effectively  doubled in the code
                execution path for this  mode.   If  set  to
                PostMilter,  sendmail  defers  synchronizing
                the queue file until any milters  have  sig-
                naled acceptance of the message.  PostMilter
                is useful only when sendmail is  running  as
                an  SMTP  server; in all other situations it
                acts the same as True.

      TLSSrvOptions
                [no short name] List  of  options  for  SMTP
                STARTTLS for the server consisting of single
                characters with intervening white  space  or
                commas.  The flag ``V'' disables client ver-
                ification, and hence it is not  possible  to
                use  a client certificate for relaying.  The
                flag ``C'' removes the requirement  for  the
                TLS  server to have a cert.  This only works
                under very specific circumstances and should
                only  be used if the consequences are under-
                stood, e.g., clients may  not  work  with  a
                server using this.

      TempFileMode=mode
                [F]  The  file  mode  for  transcript files,
                files to which sendmail  delivers  directly,
                files  in  the HostStatusDirectory, and Sta-
                tusFile.  It is interpreted in octal by  de-
                fault.  Defaults to 0600.

      Timeout.type=timeout
                [r; subsumes old T option as well] Set time-
                out values.  For more information, see  sec-
                tion 4.1.

      TimeZoneSpec=tzinfo
                [t]  Set  the local time zone info to tzinfo
                -- for  example,  "PST8PDT".   Actually,  if
                this is not set, the TZ environment variable
                is cleared (so the system default is  used);
                if  set  but null, the user's TZ variable is
                used, and if set and non-null the  TZ  vari-
                able is set to this value.

      TrustedUser=user
                [no  short name] The user parameter may be a
                user name (looked up in  /etc/passwd)  or  a
                numeric  user  id.   Trusted  user  for file










SMM:08-128         Sendmail Installation and Operation Guide


                ownership and starting the daemon.  If  set,
                generated  alias  databases  and the control
                socket (if configured) will automatically be
                owned by this user.

      TryNullMXList
                [w]  If  this system is the "best" (that is,
                lowest preference) MX for a given host,  its
                configuration  rules  should normally detect
                this situation and treat that condition spe-
                cially  by  forwarding  the  mail  to a UUCP
                feed, treating it  as  local,  or  whatever.
                However,  in  some  cases  (such as Internet
                firewalls) you may want to  try  to  connect
                directly to that host as though it had no MX
                records at all.  Setting this option  causes
                sendmail  to try this.  The downside is that
                errors in your configuration are  likely  to
                be  diagnosed  as "host unknown" or "message
                timed out" instead of something  more  mean-
                ingful.  This option is disrecommended.

      UnixFromLine=fromline
                [$l  macro]  Defines  the  format  used when
                sendmail must add a  UNIX-style  From_  line
                (that      is,      a     line     beginning
                "From<space>user").  Defaults  to  "From  $g
                $d".   Don't  change this unless your system
                uses a different UNIX mailbox  format  (very
                unlikely).

      UnsafeGroupWrites
                [no  short name] If set (default), :include:
                and .forward files that are  group  writable
                are  considered "unsafe", that is, they can-
                not reference programs or write directly  to
                files.   World  writable :include: and .for-
                ward files are  always  unsafe.   Note:  use
                DontBlameSendmail  instead;  this  option is
                deprecated.

      UseCompressedIPv6Addresses
                [no short name] If set, the compressed  for-
                mat  of  IPv6  addresses,  such as IPV6:::1,
                will be used, instead  of  the  uncompressed
                format, such as IPv6:0:0:0:0:0:0:0:1.

      UseErrorsTo
                [l] If there is an "Errors-To:" header, send
                error  messages  to  the  addresses   listed
                there.   They  normally  go  to the envelope
                sender.  Use of this option causes  sendmail
                to   violate   RFC  1123.   This  option  is










Sendmail Installation and Operation Guide         SMM:08-129


                disrecommended and deprecated.

      UserDatabaseSpec=udbspec
                [U] The user database specification.

      Verbose   [v] Run in verbose mode.  If  this  is  set,
                sendmail  adjusts options HoldExpensive (old
                c) and DeliveryMode (old d) so that all mail
                is  delivered  completely in a single job so
                that  you  can  see  the   entire   delivery
                process.  Option Verbose should never be set
                in the configuration file;  it  is  intended
                for  command  line  use only.  Note that the
                use of option Verbose can cause  authentica-
                tion information to leak, if you use a send-
                mail client to authenticate to a server.  If
                the authentication mechanism uses plain text
                passwords (as with LOGIN or PLAIN), then the
                password  could  be  compromised.   To avoid
                this, do not  install  sendmail  set-user-ID
                root, and disable the VERB SMTP command with
                a suitable PrivacyOptions setting.

      XscriptFileBufferSize=threshold
                [no short name] Set the threshold, in bytes,
                before  a memory-based queue transcript file
                becomes disk-based.   The  default  is  4096
                bytes.

      All options can be specified on the command line using
      the -O or -o flag, but most will cause sendmail to re-
      linquish  its  set-user-ID  permissions.   The options
      that will not cause this are SevenBitInput [7], Eight-
      BitMode  [8],  MinFreeBlocks  [b],  CheckpointInterval
      [C], DeliveryMode [d], ErrorMode [e], IgnoreDots  [i],
      SendMimeErrors [j], LogLevel [L], MeToo [m], OldStyle-
      Headers [o], PrivacyOptions [p], SuperSafe  [s],  Ver-
      bose [v], QueueSortOrder, MinQueueAge, DefaultCharSet,
      Dial    Delay,    NoRecipientAction,    ColonOkInAddr,
      MaxQueueRunSize,  SingleLineFromHeader,  and  AllowBo-
      gusHELO.  Actually, PrivacyOptions [p]  given  on  the
      command  line  are added to those already specified in
      the sendmail.cf  file,  i.e.,  they  can't  be  reset.
      Also, M (define macro) when defining the r or s macros
      is also considered "safe".

   5.7.  P -- Precedence Definitions

           Values for the "Precedence:" field may be defined
      using  the  P  control line.  The syntax of this field
      is:

          Pname=num










SMM:08-130         Sendmail Installation and Operation Guide


      When the name is found in a "Precedence:"  field,  the
      message  class  is  set  to  num.  Higher numbers mean
      higher precedence.  Numbers less than  zero  have  the
      special  property  that if an error occurs during pro-
      cessing the body of the message will not be  returned;
      this  is  expected  to be used for "bulk" mail such as
      through mailing  lists.   The  default  precedence  is
      zero.  For example, our list of precedences is:

          Pfirst-class=0
          Pspecial-delivery=100
          Plist=-30
          Pbulk=-60
          Pjunk=-100

      People  writing  mailing list exploders are encouraged
      to use "Precedence: list".  Older versions of sendmail
      (which discarded all error returns for negative prece-
      dences) didn't recognize this name, giving  it  a  de-
      fault  precedence of zero.  This allows list maintain-
      ers to see error returns on both old and new  versions
      of sendmail.

   5.8.  V -- Configuration Version Level

           To  provide  compatibility with old configuration
      files, the V line has been added to define  some  very
      basic  semantics of the configuration file.  These are
      not intended to be long term  supports;  rather,  they
      describe compatibility features which will probably be
      removed in future releases.

           N.B.: these version levels  have  nothing  to  do
      with the version number on the files.  For example, as
      of this writing version 10 config files (specifically,
      8.10) used version level 9 configurations.

           "Old"  configuration files are defined as version
      level one.  Version level two files make the following
      changes:

       (1)   Host  name canonification ($[ ... $]) appends a
             dot if the name is recognized; this  gives  the
             config  file  a  way of finding out if anything
             matched.  (Actually, this just initializes  the
             "host"  map with the "-a."  flag -- you can re-
             set it to anything you prefer by declaring  the
             map explicitly.)

       (2)   Default   host  name  extension  is  consistent
             throughout processing; version level  one  con-
             figurations  turned  off domain extension (that
             is,  adding  the  local  domain  name)   during










Sendmail Installation and Operation Guide         SMM:08-131


             certain  points  in  processing.  Version level
             two configurations are expected  to  include  a
             trailing  dot  to indicate that the name is al-
             ready canonical.

       (3)   Local names that are  not  aliases  are  passed
             through  a new distinguished ruleset five; this
             can be used to append a local relay.  This  be-
             havior  can be prevented by resolving the local
             name with an initial `@'.  That  is,  something
             that resolves to a local mailer and a user name
             of "vikki" will be passed through ruleset five,
             but  a  user name of "@vikki" will have the `@'
             stripped, will not be  passed  through  ruleset
             five, but will otherwise be treated the same as
             the prior example.   The  expectation  is  that
             this  might be used to implement a policy where
             mail sent to "vikki" was handled by  a  central
             hub, but mail sent to "vikki@localhost" was de-
             livered directly.

           Version level three files allow # initiated  com-
      ments  on all lines.  Exceptions are backslash escaped
      # marks and the $# syntax.

           Version level four configurations are  completely
      equivalent to level three for historical reasons.

           Version level five configuration files change the
      default definition of $w to be just the  first  compo-
      nent of the hostname.

           Version level six configuration files change many
      of the local processing options (such as aliasing  and
      matching  the beginning of the address for `|' charac-
      ters) to be mailer  flags;  this  allows  fine-grained
      control  over the special local processing.  Level six
      configuration files may also use  long  option  names.
      The  ColonOkInAddr  option (to allow colons in the lo-
      cal-part of addresses) defaults on for lower  numbered
      configuration  files;  the configuration file requires
      some additional intelligence to  properly  handle  the
      RFC 822 group construct.

           Version  level seven configuration files used new
      option names to replace old macros  ($e  became  Smtp-
      GreetingMessage, $l became UnixFromLine, and $o became
      OperatorChars.  Also, prior to version seven, the  F=q
      flag  (use  250  instead  of 252 return value for SMTP
      VRFY commands) was assumed.

           Version level eight configuration files allow  $#
      on the left hand side of ruleset lines.










SMM:08-132         Sendmail Installation and Operation Guide


           Version  level  nine  configuration  files  allow
      parentheses in rulesets, i.e. they are not treated  as
      comments and hence removed.

           Version level ten configuration files allow queue
      group definitions.

           The V line may have an optional /vendor to  indi-
      cate  that  this configuration file uses modifications
      specific  to  a  particular  vendor[22].   You may use
      "/Berkeley" to emphasize that this configuration  file
      uses the Berkeley dialect of sendmail.

   5.9.  K -- Key File Declaration

           Special maps can be defined using the line:

          Kmapname mapclass arguments

      The  mapname is the handle by which this map is refer-
      enced in the rewriting rules.   The  mapclass  is  the
      name  of a type of map; these are compiled in to send-
      mail.  The arguments are interpreted depending on  the
      class;  typically,  there  would  be a single argument
      naming the file containing the map.

           Maps are referenced using the syntax:

          $( map key $@ arguments $: default $)

      where either or both of the arguments or default  por-
      tion may be omitted.  The $@ arguments may appear more
      than once.  The indicated key and arguments are passed
      to  the appropriate mapping function.  If it returns a
      value, it replaces the input.  If it does not return a
      value  and  the  default is specified, the default re-
      places the input.  Otherwise, the input is unchanged.

           The arguments are passed to the map for arbitrary
      use.  Most map classes can interpolate these arguments
      into their values using the syntax "%n" (where n is  a
      digit)  to indicate the corresponding argument.  Argu-
      ment "%0" indicates the database  key.   For  example,
      the rule

          R$- ! $+       $: $(uucp $1 $@ $2 $: $2 @ $1 . UUCP $)
____________________
   [22]And of course, vendors are encouraged  to  add  them-
selves to the list of recognized vendors by editing the rou-
tine setvendor in  conf.c.   Please  send  e-mail  to  send-
mail@Sendmail.ORG to register your vendor dialect.












Sendmail Installation and Operation Guide         SMM:08-133


      Looks  up  the UUCP name in a (user defined) UUCP map;
      if not found it turns it into ".UUCP" form.  The data-
      base might contain records like:

          decvax         %1@%0.DEC.COM
          research       %1@%0.ATT.COM

      Note that default clauses never do this mapping.

           The  built-in map with both name and class "host"
      is the host name canonicalization lookup.   Thus,  the
      syntax:

          $(host hostname$)

      is equivalent to:

          $[hostname$]


           There are many defined classes.

      dbm       Database  lookups using the ndbm(3) library.
                Sendmail must be compiled with NDBM defined.

      btree     Database lookups using the  btree  interface
                to  the  Berkeley DB library.  Sendmail must
                be compiled with NEWDB defined.

      hash      Database lookups using the hash interface to
                the  Berkeley  DB library.  Sendmail must be
                compiled with NEWDB defined.

      nis       NIS lookups.  Sendmail must be compiled with
                NIS defined.

      nisplus   NIS+  lookups.   Sendmail  must  be compiled
                with NISPLUS defined.  The argument  is  the
                name  of  the  table to use for lookups, and
                the -k and -v flags may be used to  set  the
                key and value columns respectively.

      hesiod    Hesiod  lookups.   Sendmail must be compiled
                with HESIOD defined.

      ldap      LDAP X500 directory lookups.  Sendmail  must
                be  compiled  with LDAPMAP defined.  The map
                supports most of the standard arguments  and
                most  of  the  command line arguments of the
                ldapsearch program.  Note that, by  default,
                if  a  single query matches multiple values,
                only the first value will be returned unless
                the  -z  (value  separator) map flag is set.










SMM:08-134         Sendmail Installation and Operation Guide


                Also, the -1 map flag will treat a  multiple
                value return as if there were no matches.

      netinfo   NeXT NetInfo lookups.  Sendmail must be com-
                piled with NETINFO defined.

      text      Text file lookups.  The format of  the  text
                file  is  defined  by the -k (key field num-
                ber), -v (value field number), and -z (field
                delimiter) flags.

      ph        PH  query map.  Contributed and supported by
                Mark Roth, roth@uiuc.edu.  For more informa-
                tion,  consult  the  web  site  "http://www-
                dev.cites.uiuc.edu/sendmail/".

      nsd       nsd map for IRIX 6.5 and later.  Contributed
                and   supported   by   Bob   Mende  of  SGI,
                mende@sgi.com.

      stab      Internal symbol table lookups.  Used  inter-
                nally for aliasing.

      implicit  Really  should  be called "alias" -- this is
                used to get the default  lookups  for  alias
                files,  and  is  the  default if no class is
                specified for alias files.

      user      Looks up users using  getpwnam(3).   The  -v
                flag  can be used to specify the name of the
                field to return (although this  is  normally
                used only to check the existence of a user).

      host      Canonifies  host domain names.  Given a host
                name it calls the name server  to  find  the
                canonical name for that host.

      bestmx    Returns  the  best MX record for a host name
                given as the key.  The  current  machine  is
                always  preferred -- that is, if the current
                machine is one of the hosts listed as a low-
                est-preference  MX  record,  then it will be
                guaranteed to be returned.  This can be used
                to  find  out  if this machine is the target
                for an MX record, and mail can  be  accepted
                on  that  basis.   If  the -z flag is given,
                then all MX names are returned, separated by
                the given delimiter.

      dns       This  map  requires the option -R to specify
                the DNS resource record type to lookup.  The
                following  types  are  supported:  A,  AAAA,
                AFSDB, CNAME, MX, NS, PTR, SRV, and TXT.   A










Sendmail Installation and Operation Guide         SMM:08-135


                map  lookup  will  return  only  one record.
                Hence for some types, e.g., MX records,  the
                return  value  might  be a random element of
                the list due to randomizing in the  DNS  re-
                solver.

      arpa      Returns  the  ``reverse''  for  the given IP
                (IPv4 or IPv6) address, i.e., the string for
                the   PTR   lookup,   but  without  trailing
                ip6.arpa or in-addr.arpa.  For example,  the
                following configuration lines:

                    Karpa arpa
                    SArpa
                    R$+            $: $(arpa $1 $)

                work like this in test mode:

                    sendmail -bt
                    ADDRESS TEST MODE (ruleset 3 NOT automatically invoked)
                    Enter <ruleset> <address>
                    > Arpa IPv6:1:2:dead:beef:9876:0:0:1
                    Arpa               input: IPv6 : 1 : 2 : dead : beef : 9876 : 0 : 0 : 1
                    Arpa             returns: 1 . 0 . 0 . 0 . 0 . 0 . 0 . 0 . 0 . 0 . 0 . 0 . 6 . 7 . 8 . 9 . f . e . e . b . d . a . e . d . 2 . 0 . 0 . 0 . 1 . 0 . 0 . 0
                    > Arpa 1.2.3.4
                    Arpa               input: 1 . 2 . 3 . 4
                    Arpa             returns: 4 . 3 . 2 . 1


      sequence  The  arguments on the `K' line are a list of
                maps; the resulting map searches  the  argu-
                ment  maps  in  order until it finds a match
                for the indicated key.  For example, if  the
                key definition is:

                    Kmap1 ...
                    Kmap2 ...
                    Kseqmap sequence map1 map2

                then  a lookup against "seqmap" first does a
                lookup in map1.  If that is  found,  it  re-
                turns  immediately.  Otherwise, the same key
                is used for map2.

      syslog    the  key  is  logged  via  syslogd(8).   The
                lookup returns the empty string.

      switch    Much like the "sequence" map except that the
                order of maps is determined by  the  service
                switch.   The  argument  is  the name of the
                service to be looked up; the values from the
                service  switch are appended to the map name
                to  create  new  map  names.   For  example,










SMM:08-136         Sendmail Installation and Operation Guide


                consider the key definition:

                    Kali switch aliases

                together with the service switch entry:

                    aliases        nis files

                This causes a query against the map "ali" to
                search maps named "ali.nis" and  "ali.files"
                in that order.

      dequote   Strip  double  quotes  (")  from a name.  It
                does not strip  backslashes,  and  will  not
                strip  quotes  if the resulting string would
                contain unscannable syntax (that  is,  basic
                errors  like unbalanced angle brackets; more
                sophisticated errors such as  unknown  hosts
                are  not  checked).   The  intent is for use
                when trying to accept mail from systems such
                as  DECnet  that  routinely quote odd syntax
                such as

                    "49ers::ubell"

                A typical usage is probably something like:

                    Kdequote dequote

                    ...

                    R$-            $: $(dequote $1 $)
                    R$- $+         $: $>3 $1 $2

                Care must be taken to prevent unexpected re-
                sults; for example,

                    "|someprogram < input > output"

                will have quotes stripped, but the result is
                probably not what you had in  mind.   Fortu-
                nately these cases are rare.

      regex     The  map definition on the K line contains a
                regular expression.  Any key input  is  com-
                pared  to  that  expression  using the POSIX
                regular  expressions   routines   regcomp(),
                regerr(), and regexec().  Refer to the docu-
                mentation for those routines for more infor-
                mation  about  the regular expression match-
                ing.  No rewriting of the key is done if the
                -m  flag  is  used.   Without it, the key is
                discarded  or  if  -s   if   used,   it   is










Sendmail Installation and Operation Guide         SMM:08-137


                substituted by the substring matches, delim-
                ited by $| or the string specified with  the
                the  -d  flag.   The flags available for the
                map are

                    -n  not
                    -f  case sensitive
                    -b  basic regular expressions (default is extended)
                    -s  substring match
                    -d  set the delimiter used for -s
                    -a  append string to key
                    -m  match only, do not replace/discard value
                    -D  perform no lookup in deferred delivery mode.

                The -s flag can include an optional  parame-
                ter  which  can  be  used to select the sub-
                strings in the result of  the  lookup.   For
                example,

                    -s1,3,4

                Notes: to match a $ in a string, \$$ must be
                used.  If the pattern contains spaces,  they
                must be replaced with the blank substitution
                character, unless it is space itself.

      program   The arguments on the K line are the pathname
                to  a  program and any initial parameters to
                be passed.  When the map is called, the  key
                is  added  to the initial parameters and the
                program is invoked as the default user/group
                id.   The  first  line of standard output is
                returned as the value of the  lookup.   This
                has  many  potential  security problems, and
                has terrible performance; it should be  used
                only when absolutely necessary.

      macro     Set or clear a macro value.  To set a macro,
                pass the value as the first argument in  the
                map  lookup.   To clear a macro, do not pass
                an argument in the map lookup.  The map  al-
                ways  returns  the empty string.  Example of
                typical usage include:




















SMM:08-138         Sendmail Installation and Operation Guide


                    Kstorage macro

                    ...

                    # set macro ${MyMacro} to the ruleset match
                    R$+ $: $(storage {MyMacro} $@ $1 $) $1
                    # set macro ${MyMacro} to an empty string
                    R$* $: $(storage {MyMacro} $@ $) $1
                    # clear macro ${MyMacro}
                    R$- $: $(storage {MyMacro} $) $1


      arith     Perform simple arithmetic  operations.   The
                operation  is  given as key, currently +, -,
                *, /, %, |, & (bitwise OR, AND), l (for less
                than),  =, and r (for random) are supported.
                The two operands  are  given  as  arguments.
                The  lookup returns the result of the compu-
                tation, i.e., TRUE or FALSE for comparisons,
                integer  values  otherwise.   The r operator
                returns a pseudo-random number  whose  value
                lies  between  the  first and second operand
                (which requires that the  first  operand  is
                smaller than the second).  All options which
                are possible for maps are ignored.  A simple
                example is:

                    Kcomp arith

                    ...

                    Scheck_etrn
                    R$* $: $(comp l $@ $&{load_avg} $@ 7 $) $1
                    RFALSE$# error ...


      socket    The  socket  map uses a simple request/reply
                protocol over TCP or UNIX domain sockets  to
                query an external server.  Both requests and
                replies are text based and encoded  as  net-
                strings,  i.e.,  a  string "hello there" be-
                comes:

                    11:hello there,

                Note: neither requests nor replies end  with
                CRLF.

                The  request  consists  of  the database map
                name and the lookup key separated by a space
                character:












Sendmail Installation and Operation Guide         SMM:08-139


                    <mapname> ' ' <key>


                The  server responds with a status indicator
                and the result (if any):


                    <status> ' ' <result>


                The status indicator specifies the result of
                the  lookup  operation  itself and is one of
                the following upper case words:

                    OK       the key was found, result contains the looked up value
                    NOTFOUND the key was not found, the result is empty
                    TEMP     a temporary failure occured
                    TIMEOUT  a timeout occured on the server side
                    PERM     a permanent failure occured


                In case of errors (status TEMP,  TIMEOUT  or
                PERM)  the  result  field may contain an ex-
                planatory message.  However, the explanatory
                message is not used any further by sendmail.

                Example replies:

                    31:OK resolved.address@example.com,



                    56:OK error:550 5.7.1 User does not accept mail from sender,


                in case of successful lookups, or:

                    8:NOTFOUND,


                in case the key was not found, or:

                    55:TEMP this text explains that we had a temporary failure,


                in case of a temporary map lookup failure.

                The  socket map uses the same syntax as mil-
                ters (see Section "X -- Mail Filter (Milter)
                Definitions")  to  specify  the  remote end-
                point, e.g.,

                    Ksocket mySocketMap inet:12345@127.0.0.1










SMM:08-140         Sendmail Installation and Operation Guide


                If multiple socket maps define the same  re-
                mote endpoint, they will share a single con-
                nection to this endpoint.

           Most of these accept as arguments  the  same  op-
      tional flags and a filename (or a mapname for NIS; the
      filename is the root of the  database  path,  so  that
      ".db"  or  some  other  extension  appropriate for the
      database type will be added to get the actual database
      name).  Known flags are:

      -o        Indicates  that this map is optional -- that
                is, if it cannot be opened, no error is pro-
                duced,  and  sendmail  will behave as if the
                map existed but was empty.

      -N, -O    If neither -N or -O are specified,  sendmail
                uses an adaptive algorithm to decide whether
                or not to look for null bytes on the end  of
                keys.  It starts by trying both; if it finds
                any key with a  null  byte  it  never  tries
                again  without  a  null byte and vice versa.
                If -N is specified it never tries without  a
                null  byte  and  if -O is specified it never
                tries with a  null  byte.   Setting  one  of
                these can speed matches but are never neces-
                sary.  If both  -N  and  -O  are  specified,
                sendmail  will  never try any matches at all
                -- that is, everything will appear to fail.

      -ax       Append the string x on  successful  matches.
                For  example, the default host map appends a
                dot on successful matches.

      -Tx       Append the string x on  temporary  failures.
                For  example,  x  would be appended if a DNS
                lookup returned "server failed"  or  an  NIS
                lookup  could not locate a server.  See also
                the -t flag.

      -f        Do not fold upper to lower case before look-
                ing up the key.

      -m        Match  only  (without  replacing the value).
                If you only care about the  existence  of  a
                key  and  not  the  value (as you might when
                searching the NIS map "hosts.byname" for ex-
                ample), this flag prevents the map from sub-
                stituting the value.  However, The -a  argu-
                ment  is  still appended on a match, and the
                default is still taken if the match fails.












Sendmail Installation and Operation Guide         SMM:08-141


      -kkeycol  The key column name  (for  NIS+)  or  number
                (for  text  lookups).  For LDAP maps this is
                an LDAP filter string in  which  %s  is  re-
                placed  with  the  literal  contents  of the
                lookup key and %0 is replaced with the  LDAP
                escaped contents of the lookup key according
                to RFC 2254.  If the flag -K is  used,  then
                %1 through %9 are replaced with the LDAP es-
                caped contents of the arguments specified in
                the map lookup.

      -vvalcol  The  value  column name (for NIS+) or number
                (for text lookups).  For LDAP maps  this  is
                the name of one or more attributes to be re-
                turned; multiple attributes can be separated
                by commas.  If not specified, all attributes
                found in the match will  be  returned.   The
                attributes  listed  can  also include a type
                and  one  or  more  objectClass  values  for
                matching as described in the LDAP section.

      -zdelim   The column delimiter (for text lookups).  It
                can be a single character or one of the spe-
                cial  strings  "\n" or "\t" to indicate new-
                line or tab respectively.   If  omitted  en-
                tirely, the column separator is any sequence
                of white space.  For LDAP maps this  is  the
                separator character to combine multiple val-
                ues into a single  return  string.   If  not
                set,  the  LDAP  lookup will only return the
                first match found.  For DNS maps this is the
                separator character at which the result of a
                query is cut off if is too long.

      -t        Normally, when a map attempts to do a lookup
                and   the   server   fails  (e.g.,  sendmail
                couldn't contact any name  server;  this  is
                not  the same as an entry not being found in
                the map), the  message  being  processed  is
                queued  for  future processing.  The -t flag
                turns off this behavior, letting the  tempo-
                rary  failure (server down) act as though it
                were a permanent failure (entry not  found).
                It  is  particularly useful for DNS lookups,
                where  someone  else's  misconfigured   name
                server  can  cause problems on your machine.
                However, care must be taken to  ensure  that
                you don't bounce mail that would be resolved
                correctly if  you  tried  again.   A  common
                strategy is to forward such mail to another,
                possibly better connected, mail server.












SMM:08-142         Sendmail Installation and Operation Guide


      -D        Perform no lookup in deferred delivery mode.
                This  flag  is  set  by default for the host
                map.

      -Sspacesub
                The character to use to replace space  char-
                acters  after  a successful map lookup (esp.
                useful for regex and syslog maps).

      -sspacesub
                For the dequote map only, the  character  to
                use to replace space characters after a suc-
                cessful dequote.

      -q        Don't dequote the key before lookup.

      -Llevel   For the syslog map only,  it  specifies  the
                level to use for the syslog call.

      -A        When  rebuilding  an alias file, the -A flag
                causes duplicate entries in the text version
                to be merged.  For example, two entries:

                    list:    user1, user2
                    list:    user3

                would  be treated as though it were the sin-
                gle entry

                    list:    user1, user2, user3

                in the presence of the -A flag.

           Some additional flags are available for the  host
      and dns maps:

      -d        delay: specify the resolver's retransmission
                time interval (in seconds).

      -r        retry: specify the number of  times  to  re-
                transmit a resolver query.

           The dns map has another flag:

      -B        basedomain:  specify a domain that is always
                appended to queries.

           Socket maps have an optional flag:

      -d        timeout: specify the  timeout  (in  seconds)
                for   communication   with  the  socket  map
                server.











Sendmail Installation and Operation Guide         SMM:08-143


           The following additional flags are present in the
      ldap map only:

      -R        Do  not auto chase referrals.  sendmail must
                be compiled  with  -DLDAP_REFERRALS  to  use
                this flag.

      -n        Retrieve attribute names only.

      -Vsep     Retrieve  both attributes name and value(s),
                separated by sep.

      -rderef   Set the alias dereference option to  one  of
                never, always, search, or find.

      -sscope   Set  search  scope  to one of base, one (one
                level), or sub (subtree).

      -hhost    LDAP server hostname.  Some  LDAP  libraries
                allow  you  to specify multiple, space-sepa-
                rated hosts for  redundancy.   In  addition,
                each  of the hosts listed can be followed by
                a colon and a port number  to  override  the
                default LDAP port.

      -pport    LDAP service port.

      -H LDAPURI
                Use the specified LDAP URI instead of speci-
                fying the hostname and port separately  with
                the  the -h and -p options shown above.  For
                example,

                    -h server.example.com -p 389 -b dc=example,dc=com

                is equivalent to

                    -H ldap://server.example.com:389 -b dc=example,dc=com

                If the LDAP library supports  it,  the  LDAP
                URI  format  however  can  also request LDAP
                over  SSL  by  using  ldaps://  instead   of
                ldap://.  For example:

                    O LDAPDefaultSpec=-H ldaps://ldap.example.com -b dc=example,dc=com

                Similarly,  if the LDAP library supports it,
                It can also be used to specify a UNIX domain
                socket using ldapi://:

                    O LDAPDefaultSpec=-H ldapi://socketfile -b dc=example,dc=com












SMM:08-144         Sendmail Installation and Operation Guide


      -bbase    LDAP search base.

      -ltimelimit
                Time limit for LDAP queries.

      -Zsizelimit
                Size  (number  of matches) limit for LDAP or
                DNS queries.

      -ddistinguished_name
                The distinguished name to use  to  login  to
                the LDAP server.

      -Mmethod  The  method  to  authenticate  to  the  LDAP
                server.  Should be  one  of  LDAP_AUTH_NONE,
                LDAP_AUTH_SIMPLE, or LDAP_AUTH_KRBV4.

      -Ppasswordfile
                The  file  containing the secret key for the
                LDAP_AUTH_SIMPLE  authentication  method  or
                the  name  of  the  Kerberos ticket file for
                LDAP_AUTH_KRBV4.

      -1        Force LDAP searches to  only  succeed  if  a
                single  match  is found.  If multiple values
                are found, the search is treated  as  if  no
                match was found.

      -wversion Set  the  LDAP  API/protocol version to use.
                The default depends on the LDAP  client  li-
                braries  in  use.   For  example,  -w 3 will
                cause sendmail to use LDAPv3  when  communi-
                cating with the LDAP server.

      -K        Treat  the LDAP search key as multi-argument
                and replace %1 through %9 in  the  key  with
                the  LDAP escaped contents of the lookup ar-
                guments specified in the map lookup.

           The dbm map appends the strings ".pag" and ".dir"
      to  the given filename; the hash and btree maps append
      ".db".  For example, the map specification

          Kuucp dbm -o -N /etc/mail/uucpmap

      specifies an optional map named "uucp" of class "dbm";
      it  always  has null bytes at the end of every string,
      and      the      data       is       located       in
      /etc/mail/uucpmap.{dir,pag}.

           The  program  makemap(8) can be used to build any
      of the three database-oriented  maps.   It  takes  the
      following flags:










Sendmail Installation and Operation Guide         SMM:08-145


      -f        Do not fold upper to lower case in the map.

      -N        Include null bytes in keys.

      -o        Append to an existing (old) file.

      -r        Allow  replacement  of  existing  keys; nor-
                mally, re-inserting an existing  key  is  an
                error.

      -v        Print what is happening.

      The  sendmail  daemon does not have to be restarted to
      read the new maps as long as you change them in place;
      file  locking  is  used so that the maps won't be read
      while they are being updated.

           New classes can be added in the routine setupmaps
      in file conf.c.

   5.10.  Q -- Queue Group Declaration

           In  addition  to the option QueueDirectory, queue
      groups can be declared that define a (group of)  queue
      directories  under  a  common  name.  The syntax is as
      follows:

          Qname {, field=value}+

      where name is the symbolic name of the queue group un-
      der  which  it can be referenced in various places and
      the "field=value" pairs define attributes of the queue
      group.   The  name  must  only consist of alphanumeric
      characters.  Fields are:

      Flags     Flags for this queue group.

      Nice      The nice(2) increment for the  queue  group.
                This value must be greater or equal zero.

      Interval  The time between two queue runs.

      Path      The queue directory of the group (required).

      Runners   The  number  of  parallel runners processing
                the queue.  Note that F=f  must  be  set  if
                this value is greater than one.

      Jobs      The  maximum number of jobs (messages deliv-
                ered) per queue run.

      recipients
                The  maximum  number   of   recipients   per










SMM:08-146         Sendmail Installation and Operation Guide


                envelope.   Envelopes  with  more  than this
                number of recipients will be split into mul-
                tiple envelopes in the same queue directory.
                The default value 0 means no limit.

      Only the first character of the field name is checked.

           By default, a queue group named mqueue is defined
      that  uses  the  value of the QueueDirectory option as
      path.  Notice: all  paths  that  are  used  for  queue
      groups   must  be  subdirectories  of  QueueDirectory.
      Since they can be symbolic links, this  isn't  a  real
      restriction,  If  QueueDirectory uses a wildcard, then
      the directory one level up is considered the  ``base''
      directory  which  all  other  queue  directories  must
      share.  Please make sure that the queue directories do
      not overlap, e.g., do not specify

          O QueueDirectory=/var/spool/mqueue/*
          Qone, P=/var/spool/mqueue/dir1
          Qtwo, P=/var/spool/mqueue/dir2

      because  this  also  includes "dir1" and "dir2" in the
      default queue group.  However,

          O QueueDirectory=/var/spool/mqueue/main*
          Qone, P=/var/spool/mqueue/dir
          Qtwo, P=/var/spool/mqueue/other*

      is a valid queue group specification.

           Options listed in the ``Flags'' field can be used
      to  modify  the  behavior of a queue group.  The ``f''
      flag must be set if multiple queue  runners  are  sup-
      posed to work on the entries in a queue group.  Other-
      wise sendmail will work on the  entries  strictly  se-
      quentially.

           The  ``Interval''  field  sets  the  time between
      queue runs.  If no queue group  specific  interval  is
      set, then the parameter of the -q option from the com-
      mand line is used.

           To control the overall number of concurrently ac-
      tive  queue runners the option MaxQueueChildren can be
      set.  This limits the number  of  processes  used  for
      running  the queues to MaxQueueChildren, though at any
      one time fewer processes may be active as a result  of
      queue options, completed queue runs, system load, etc.

           The  maximum number of queue runners for an indi-
      vidual queue group can be controlled via  the  Runners
      option.  If set to 0, entries in the queue will not be










Sendmail Installation and Operation Guide         SMM:08-147


      processed, which is  useful  to  ``quarantine''  queue
      files.  The number of runners per queue group may also
      be set with the option MaxRunnersPerQueue,  which  ap-
      plies  to  queue groups that have no individual limit.
      That is, the default  value  for  Runners  is  MaxRun-
      nersPerQueue if set, otherwise 1.

           The  field  Jobs  describes the maximum number of
      jobs (messages delivered) per queue run, which is  the
      queue group specific value of MaxQueueRunSize.

           Notice: queue groups should be declared after all
      queue related options  have  been  set  because  queue
      groups  take their defaults from those options.  If an
      option is set after a  queue  group  declaration,  the
      values  of  options  in the queue group are set to the
      defaults of sendmail unless explicitly set in the dec-
      laration.

           Each  envelope is assigned to a queue group based
      on the algorithm described in section  ``Queue  Groups
      and Queue Directories''.

   5.11.  X -- Mail Filter (Milter) Definitions

           The sendmail Mail Filter API (Milter) is designed
      to allow third-party programs access to mail  messages
      as  they  are being processed in order to filter meta-
      information and content.  They  are  declared  in  the
      configuration file as:

          Xname {, field=value}*

      where  name is the name of the filter (used internally
      only) and the "field=name" pairs define attributes  of
      the filter.  Also see the documentation for the Input-
      MailFilters option for more information.

           Fields are:

          Socket    The socket specification
          Flags     Special flags for this filter
          Timeouts  Timeouts for this filter

      Only the first character of the field name is  checked
      (it's case-sensitive).

           The  socket specification is one of the following
      forms:

          S=inet: port @ host












SMM:08-148         Sendmail Installation and Operation Guide


          S=inet6: port @ host


          S=local: path

      The first two describe an IPv4 or IPv6 socket  listen-
      ing  on  a certain port at a given host or IP address.
      The  final  form  describes  a  named  socket  on  the
      filesystem at the given path.

           The  following flags may be set in the filter de-
      scription.

      R   Reject connection if filter unavailable.

      T   Temporary fail connection if filter unavailable.

           If neither F=R nor F=T is specified, the  message
      is passed through sendmail in case of filter errors as
      if the failing filters were not present.

           The timeouts can be set using the four fields in-
      side of the T= equate:

      C   Timeout  for connecting to a filter.  If set to 0,
          the system's connect() timeout will be used.

      S   Timeout for sending information from the MTA to  a
          filter.

      R   Timeout for reading reply from the filter.

      E   Overall  timeout between sending end-of-message to
          filter and waiting for the final acknowledgment.

           Note the separator between each timeout field  is
      a   ';'.    The  default  values  (if  not  set)  are:
      T=C:5m;S:10s;R:10s;E:5m where s is seconds  and  m  is
      minutes.

           Examples:

          Xfilter1, S=local:/var/run/f1.sock, F=R
          Xfilter2, S=inet6:999@localhost, F=T, T=S:1s;R:1s;E:5m
          Xfilter3, S=inet:3333@localhost, T=C:2m


   5.12.  The User Database

           The  user  database  is  deprecated  in  favor of
      ``virtusertable'' and ``genericstable''  as  explained
      in the file cf/README.  If you have a version of send-
      mail with the user database package compiled  in,  the










Sendmail Installation and Operation Guide         SMM:08-149


      handling  of  sender  and recipient addresses is modi-
      fied.

           The location of this database is controlled  with
      the UserDatabaseSpec option.

      5.12.1.  Structure of the user database

              The  database is a sorted (BTree-based) struc-
         ture.  User records are stored with the key:

             user-name:field-name

         The  sorted  database  format  ensures  that   user
         records  are  clustered together.  Meta-information
         is always stored with a leading colon.

              Field names define both the syntax and  seman-
         tics of the value.  Defined fields include:

         maildrop  The   delivery  address  for  this  user.
                   There may  be  multiple  values  of  this
                   record.   In  particular,  mailing  lists
                   will have one maildrop  record  for  each
                   user on the list.

         mailname  The outgoing mailname for this user.  For
                   each outgoing name, there  should  be  an
                   appropriate maildrop record for that name
                   to allow  return  mail.   See  also  :de-
                   fault:mailname.

         mailsender
                   Changes  any mail sent to this address to
                   have the indicated envelope sender.  This
                   is  intended  for mailing lists, and will
                   normally be the name  of  an  appropriate
                   -request  address.  It is very similar to
                   the owner-list syntax in the alias file.

         fullname  The full name of the user.

         office-address
                   The office address for this user.

         office-phone
                   The office phone number for this user.

         office-fax
                   The office FAX number for this user.

         home-address
                   The home address for this user.










SMM:08-150         Sendmail Installation and Operation Guide


         home-phone
                   The home phone number for this user.

         home-fax  The home FAX number for this user.

         project   A (short) description of the project this
                   person  is  affiliated with.  In the Uni-
                   versity this is often just  the  name  of
                   their graduate advisor.

         plan      A  pointer  to a file from which plan in-
                   formation can be gathered.

              As of this writing, only a few of these fields
         are  actually  being used by sendmail: maildrop and
         mailname.  A finger program  that  uses  the  other
         fields is planned.

      5.12.2.  User database semantics

              When  the rewriting rules submit an address to
         the local mailer, the user name is  passed  through
         the  alias  file.   If no alias is found (or if the
         alias points back to the same  address),  the  name
         (with  ":maildrop"  appended) is then used as a key
         in the user database.  If no match  occurs  (or  if
         the  maildrop points at the same address), forward-
         ing is tried.

              If the first token of the user  name  returned
         by  ruleset  0  is  an  "@" sign, the user database
         lookup is skipped.  The intent  is  that  the  user
         database  will act as a set of defaults for a clus-
         ter (in our case, the Computer  Science  Division);
         mail sent to a specific machine should ignore these
         defaults.

              When mail is sent, the  name  of  the  sending
         user  is  looked  up in the database.  If that user
         has a "mailname" record, the value of  that  record
         is  used  as  their  outgoing name.  For example, I
         might have a record:

             eric:mailnameEric.Allman@CS.Berkeley.EDU

         This would cause my outgoing mail  to  be  sent  as
         Eric.Allman.

              If  a "maildrop" is found for the user, but no
         corresponding "mailname" record exists, the  record
         ":default:mailname" is consulted.  If present, this
         is the name of a host to override the  local  host.
         For  example,  in  our  case  we  would  set  it to










Sendmail Installation and Operation Guide         SMM:08-151


         "CS.Berkeley.EDU".  The effect is that anyone known
         in the database gets their outgoing mail stamped as
         "user@CS.Berkeley.EDU", but people  not  listed  in
         the database use the local hostname.

      5.12.3.  Creating the database[23]

              The user database is built from  a  text  file
         using  the  makemap utility (in the distribution in
         the makemap subdirectory).  The text file is a  se-
         ries of lines corresponding to userdb records; each
         line has a key  and  a  value  separated  by  white
         space.   The  key is always in the format described
         above -- for example:

             eric:maildrop

         This file is normally installed in a system  direc-
         tory;    for    example,   it   might   be   called
         /etc/mail/userdb.  To make the database version  of
         the map, run the program:

             makemap btree /etc/mail/userdb < /etc/mail/userdb

         Then  create a config file that uses this.  For ex-
         ample, using the V8 M4 configuration,  include  the
         following line in your .mc file:

             define(`confUSERDB_SPEC', /etc/mail/userdb)


6.  OTHER CONFIGURATION

        There  are  some  configuration  changes that can be
   made by recompiling  sendmail.   This  section  describes
   what  changes  can be made and what has to be modified to
   make them.  In most cases this should be unnecessary  un-
   less you are porting sendmail to a new environment.

   6.1.  Parameters in devtools/OS/$oscf

           These  parameters  are  intended  to describe the
      compilation environment, not site policy,  and  should
      normally be defined in the operating system configura-
      tion file.  This section needs a complete rewrite.

____________________
   [23]These instructions are known to be incomplete.  Other
features are available which provide similar  functionality,
e.g.,  virtual  hosting  and  mapping local addresses into a
generic form as explained in cf/README.












SMM:08-152         Sendmail Installation and Operation Guide


      NDBM      If set, the new version of the  DBM  library
                that allows multiple databases will be used.
                If neither NDBM nor NEWDB are  set,  a  much
                less  efficient  method  of  alias lookup is
                used.

      NEWDB     If set, use the new  database  package  from
                Berkeley  (from  4.4BSD).   This  package is
                substantially faster than DBM or  NDBM.   If
                NEWDB  and  NDBM are both set, sendmail will
                read DBM files,  but  will  create  and  use
                NEWDB files.

      NIS       Include  support  for  NIS.  If set together
                with both NEWDB and NDBM, sendmail will cre-
                ate  both DBM and NEWDB files if and only if
                an alias file includes the substring  "/yp/"
                in  the name.  This is intended for compati-
                bility with Sun Microsystems'  mkalias  pro-
                gram used on YP masters.

      NISPLUS   Compile in support for NIS+.

      NETINFO   Compile  in  support  for NetInfo (NeXT sta-
                tions).

      LDAPMAP   Compile in support for  LDAP  X500  queries.
                Requires  libldap and liblber from the Umich
                LDAP 3.2 or 3.3 release  or  equivalent  li-
                braries  for  other  LDAP  libraries such as
                OpenLDAP.

      HESIOD    Compile in support for Hesiod.

      MAP_NSD   Compile in support for IRIX NSD lookups.

      MAP_REGEX Compile in support  for  regular  expression
                matching.

      DNSMAP    Compile  in  support  for DNS map lookups in
                the sendmail.cf file.

      PH_MAP    Compile in support for ph lookups.

      SASL      Compile in support for SASL, a required com-
                ponent for SMTP Authentication support.

      STARTTLS  Compile in support for STARTTLS.

      EGD       Compile  in support for the "Entropy Gather-
                ing Daemon" to provide  better  random  data
                for TLS.











Sendmail Installation and Operation Guide         SMM:08-153


      TCPWRAPPERS
                Compile in support for TCP Wrappers.

      _PATH_SENDMAILCF
                The pathname of the sendmail.cf file.

      _PATH_SENDMAILPID
                The pathname of the sendmail.pid file.

      SM_CONF_SHM
                Compile  in  support  for shared memory, see
                section about "/var/spool/mqueue".

      MILTER    Compile in support for  contacting  external
                mail filters built with the Milter API.

           There are also several compilation flags to indi-
      cate the environment such as "_AIX3" and "_SCO_unix_".
      See  the  sendmail/README file for the latest scoop on
      these flags.

      6.1.1.  For Future Releases

              sendmail often contains compile  time  options
         For  Future  Releases (prefix _FFR_) which might be
         enabled in a subsequent version or might simply  be
         removed as they turned out not to be really useful.
         These features are usually not  documented  but  if
         they  are, then the required (FFR) compile time op-
         tions are listed here for rulesets and macros,  and
         in  cf/README for mc/cf options.  FFR compile times
         options must be enabled when the sendmail binary is
         built from source.  Enabled FFRs in a binary can be
         listed with

             sendmail -d0.13 < /dev/null | grep FFR


   6.2.  Parameters in sendmail/conf.h

           Parameters and compilation options are defined in
      conf.h.   Most  of these need not normally be tweaked;
      common parameters are all  in  sendmail.cf.   However,
      the  sizes of certain primitive vectors, etc., are in-
      cluded in this file.  The numbers following the param-
      eters are their default value.

           This  document is not the best source of informa-
      tion for compilation flags  in  conf.h  --  see  send-
      mail/README or sendmail/conf.h itself.

      MAXLINE [2048]
                  The maximum line length of any input line.










SMM:08-154         Sendmail Installation and Operation Guide


                  If message lines exceed this  length  they
                  will  still  be  processed correctly; how-
                  ever,  header  lines,  configuration  file
                  lines,  alias lines, etc., must fit within
                  this limit.

      MAXNAME [256]
                  The maximum length of any name, such as  a
                  host or a user name.

      MAXPV [256] The  maximum  number  of parameters to any
                  mailer.  This limits the number of recipi-
                  ents  that  may  be passed in one transac-
                  tion.  It can be set to any arbitrary num-
                  ber  above  about  10, since sendmail will
                  break up a delivery into  smaller  batches
                  as  needed.   A  higher  number may reduce
                  load on your system, however.

      MAXQUEUEGROUPS [50]
                  The maximum number of queue groups.

      MAXATOM [1000]
                  The maximum number of atoms (tokens) in  a
                  single  address.  For example, the address
                  "eric@CS.Berkeley.EDU" is seven atoms.

      MAXMAILERS [25]
                  The maximum number of mailers that may  be
                  defined  in  the configuration file.  This
                  value is defined in include/sendmail/send-
                  mail.h.

      MAXRWSETS [200]
                  The  maximum number of rewriting sets that
                  may be defined.  The first half  of  these
                  are  reserved  for  numeric  specification
                  (e.g., ``S92''), while the upper half  are
                  reserved    for    auto-numbering   (e.g.,
                  ``Sfoo'').  Thus, with a value of  200  an
                  attempt  to  use ``S99'' will succeed, but
                  ``S100'' will fail.

      MAXPRIORITIES [25]
                  The  maximum  number  of  values  for  the
                  "Precedence:"  field  that  may be defined
                  (using the P line in sendmail.cf).

      MAXUSERENVIRON [100]
                  The maximum number of items  in  the  user
                  environment  that will be passed to subor-
                  dinate mailers.











Sendmail Installation and Operation Guide         SMM:08-155


      MAXMXHOSTS [100]
                  The maximum number of MX records  we  will
                  accept for any single host.

      MAXMAPSTACK [12]
                  The  maximum  number  of  maps that may be
                  "stacked" in a sequence class map.

      MAXMIMEARGS [20]
                  The maximum number of arguments in a  MIME
                  Content-Type: header; additional arguments
                  will be ignored.

      MAXMIMENESTING [20]
                  The maximum depth to which  MIME  messages
                  may  be nested (that is, nested Message or
                  Multipart documents; this does  not  limit
                  the  number of components in a single Mul-
                  tipart document).

      MAXDAEMONS [10]
                  The maximum  number  of  sockets  sendmail
                  will  open  for  accepting  connections on
                  different ports.

      MAXMACNAMELEN [25]
                  The maximum length of a macro name.

      A number of other compilation  options  exist.   These
      specify  whether  or  not specific code should be com-
      piled in.  Ones marked with * are 0/1 valued.

      NETINET*    If set, support for Internet protocol net-
                  working is compiled in.  Previous versions
                  of sendmail referred to  this  as  DAEMON;
                  this old usage is now incorrect.  Defaults
                  on; turn it off in the  Makefile  if  your
                  system doesn't support the Internet proto-
                  cols.

      NETINET6*   If set, support  for  IPv6  networking  is
                  compiled  in.   It  must be separately en-
                  abled  by  adding  DaemonPortOptions  set-
                  tings.

      NETISO*     If  set, support for ISO protocol network-
                  ing is compiled in (it may be  appropriate
                  to #define this in the Makefile instead of
                  conf.h).

      NETUNIX*    If set, support for UNIX domain sockets is
                  compiled  in.   This  is  used for control
                  socket support.










SMM:08-156         Sendmail Installation and Operation Guide


      LOG         If set, the syslog routine in use at  some
                  sites  is  used.   This  makes an informa-
                  tional log record for  each  message  pro-
                  cessed,  and  makes  a higher priority log
                  record   for   internal   system   errors.
                  STRONGLY  RECOMMENDED  --  if  you want no
                  logging, turn it off in the  configuration
                  file.

      MATCHGECOS* Compile  in  the code to do ``fuzzy match-
                  ing'' on the GECOS field  in  /etc/passwd.
                  This also requires that the MatchGECOS op-
                  tion be turned on.

      NAMED_BIND* Compile in code to use the Berkeley Inter-
                  net  Name  Domain (BIND) server to resolve
                  TCP/IP host names.

      NOTUNIX     If you are using a non-UNIX  mail  format,
                  you  can set this flag to turn off special
                  processing of UNIX-style "From " lines.

      USERDB*     Include the experimental Berkeley user in-
                  formation  database  package.  This adds a
                  new level of local name expansion  between
                  aliasing and forwarding.  It also uses the
                  NEWDB package.  This may change in  future
                  releases.

      The  following  options are normally turned on in per-
      operating-system clauses in conf.h.

      IDENTPROTO* Compile in the IDENT protocol  as  defined
                  in  RFC  1413.   This  defaults on for all
                  systems except  Ultrix,  which  apparently
                  has the interesting "feature" that when it
                  receives a "host unreachable"  message  it
                  closes  all open connections to that host.
                  Since some firewall gateways send this er-
                  ror  code  when you access an unauthorized
                  port (such as 113, used by IDENT),  Ultrix
                  cannot receive email from such hosts.

      SYSTEM5     Set  all of the compilation parameters ap-
                  propriate for System V.

      HASFLOCK*   Use Berkeley-style flock instead of System
                  V  lockf  to  do file locking.  Due to the
                  highly unusual semantics of  locks  across
                  forks in lockf, this should always be used
                  if at all possible.












Sendmail Installation and Operation Guide         SMM:08-157


      HASINITGROUPS
                  Set this if  your  system  has  the  init-
                  groups()  call (if you have multiple group
                  support).  This is the default if  SYSTEM5
                  is not defined or if you are on HPUX.

      HASUNAME    Set  this  if you have the uname(2) system
                  call (or corresponding  library  routine).
                  Set by default if SYSTEM5 is set.

      HASGETDTABLESIZE
                  Set  this if you have the getdtablesize(2)
                  system call.

      HASWAITPID  Set this if  you  have  the  haswaitpid(2)
                  system call.

      FAST_PID_RECYCLE
                  Set this if your system can possibly reuse
                  the same pid in the same second of time.

      SFS_TYPE    The mechanism that can be used to get file
                  system  capacity  information.  The values
                  can be one of SFS_USTAT (use the  ustat(2)
                  syscall), SFS_4ARGS (use the four argument
                  statfs(2) syscall), SFS_VFS (use  the  two
                  argument   statfs(2)   syscall   including
                  <sys/vfs.h>), SFS_MOUNT (use the two argu-
                  ment     statfs(2)    syscall    including
                  <sys/mount.h>), SFS_STATFS  (use  the  two
                  argument   statfs(2)   syscall   including
                  <sys/statfs.h>), SFS_STATVFS (use the  two
                  argument   statfs(2)   syscall   including
                  <sys/statvfs.h>), or SFS_NONE (no  way  to
                  get this information).

      LA_TYPE     The  load  average  type.  Details are de-
                  scribed below.

      The are several built-in ways of  computing  the  load
      average.   Sendmail tries to auto-configure them based
      on imperfect guesses; you can select one using the  cc
      option -DLA_TYPE=type, where type is:

      LA_INT      The  kernel stores the load average in the
                  kernel as an array of long integers.   The
                  actual  values  are scaled by a factor FS-
                  CALE (default 256).

      LA_SHORT    The kernel stores the load average in  the
                  kernel as an array of short integers.  The
                  actual values are scaled by a  factor  FS-
                  CALE (default 256).










SMM:08-158         Sendmail Installation and Operation Guide


      LA_FLOAT    The  kernel stores the load average in the
                  kernel as an  array  of  double  precision
                  floats.

      LA_MACH     Use MACH-style load averages.

      LA_SUBR     Call  the  getloadavg  routine  to get the
                  load average as an array of doubles.

      LA_ZERO     Always return zero as  the  load  average.
                  This is the fallback case.

      If  type  LA_INT,  LA_SHORT, or LA_FLOAT is specified,
      you may also need to specify _PATH_UNIX (the  path  to
      your  system  binary)  and LA_AVENRUN (the name of the
      variable containing the load average  in  the  kernel;
      usually "_avenrun" or "avenrun").

   6.3.  Configuration in sendmail/conf.c

           The following changes can be made in conf.c.

      6.3.1.  Built-in Header Semantics

              Not  all  header  semantics are defined in the
         configuration file.  Header lines that should  only
         be  included  by  certain mailers (as well as other
         more obscure semantics) must be  specified  in  the
         HdrInfo  table  in conf.c.  This table contains the
         header name (which should be in all lower case) and
         a  set  of  header control flags (described below),
         The flags are:

         H_ACHECK    Normally when the check is made to  see
                     if  a  header line is compatible with a
                     mailer, sendmail will not delete an ex-
                     isting  line.   If  this  flag  is set,
                     sendmail  will  delete  even   existing
                     header  lines.  That is, if this bit is
                     set and the mailer does not  have  flag
                     bits  set  that  intersect with the re-
                     quired mailer flags in the header defi-
                     nition  in sendmail.cf, the header line
                     is always deleted.

         H_EOH       If this header field is set,  treat  it
                     like a blank line, i.e., it will signal
                     the end of the header and the beginning
                     of the message text.

         H_FORCE     Add  this  header entry even if one ex-
                     isted in  the  message  before.   If  a
                     header  entry  does  not  have this bit










Sendmail Installation and Operation Guide         SMM:08-159


                     set,  sendmail  will  not  add  another
                     header  line  if  a header line of this
                     name already existed.  This would  nor-
                     mally  be  used to stamp the message by
                     everyone who handled it.

         H_TRACE     If set, this  is  a  timestamp  (trace)
                     field.   If  the number of trace fields
                     in a message exceeds  a  preset  amount
                     the  message is returned on the assump-
                     tion that it has an aliasing loop.

         H_RCPT      If set, this field  contains  recipient
                     addresses.  This is used by the -t flag
                     to determine who to send to when it  is
                     collecting recipients from the message.

         H_FROM      This  flag  indicates  that  this field
                     specifies a sender.  The order of these
                     fields  in  the HdrInfo table specifies
                     sendmail's preference for  which  field
                     to return error messages to.

         H_ERRORSTO  Addresses in this header should receive
                     error messages.

         H_CTE       This header is  a  Content-Transfer-En-
                     coding header.

         H_CTYPE     This header is a Content-Type header.

         H_STRIPVAL  Strip  the  value  from the header (for
                     Bcc:).

         Let's look at a sample HdrInfo specification:




























SMM:08-160         Sendmail Installation and Operation Guide


             struct hdrinfo                    HdrInfo[] =
             {
                      /* originator fields, most to least significant  */
                 "resent-sender",              H_FROM,
                 "resent-from",                H_FROM,
                 "sender",                     H_FROM,
                 "from",                       H_FROM,
                 "full-name",                  H_ACHECK,
                 "errors-to",                  H_FROM|H_ERRORSTO,
                      /* destination fields */
                 "to",                         H_RCPT,
                 "resent-to",                  H_RCPT,
                 "cc",                         H_RCPT,
                 "bcc",                        H_RCPT|H_STRIPVAL,
                      /* message identification and control */
                 "message",                    H_EOH,
                 "text",                       H_EOH,
                      /* trace fields */
                 "received",                   H_TRACE|H_FORCE,
                      /* miscellaneous fields */
                 "content-transfer-encoding",  H_CTE,
                 "content-type",               H_CTYPE,

                 NULL,                         0,
             };

         This structure indicates that the  "To:",  "Resent-
         To:",  and  "Cc:"  fields all specify recipient ad-
         dresses.  Any "Full-Name:" field  will  be  deleted
         unless  the  required mailer flag (indicated in the
         configuration file) is specified.   The  "Message:"
         and "Text:" fields will terminate the header; these
         are used by random dissenters  around  the  network
         world.  The "Received:" field will always be added,
         and can be used to trace messages.

              There are a number of important  points  here.
         First,  header  fields  are not added automatically
         just because they are  in  the  HdrInfo  structure;
         they must be specified in the configuration file in
         order to be  added  to  the  message.   Any  header
         fields  mentioned in the configuration file but not
         mentioned in the  HdrInfo  structure  have  default
         processing  performed;  that is, they are added un-
         less they were in the message already.  Second, the
         HdrInfo  structure  only specifies cliched process-
         ing; certain headers are processed specially by  ad
         hoc  code  regardless  of  the  status specified in
         HdrInfo.  For example, the  "Sender:"  and  "From:"
         fields are always scanned on ARPANET mail to deter-













Sendmail Installation and Operation Guide         SMM:08-161


         mine the sender[24]; this is used  to  perform  the
         "return  to  sender"  function.   The  "From:"  and
         "Full-Name:" fields are used to determine the  full
         name  of  the sender if possible; this is stored in
         the macro $x and used in a number of ways.

      6.3.2.  Restricting Use of Email

              If it is necessary to restrict mail through  a
         relay,  the  checkcompat  routine  can be modified.
         This routine is called for every recipient address.
         It  returns an exit status indicating the status of
         the message.  The status EX_OK accepts the address,
         EX_TEMPFAIL queues the message for a later try, and
         other values (commonly EX_UNAVAILABLE)  reject  the
         message.  It is up to checkcompat to print an error
         message (using usrerr) if the message is  rejected.
         For example, checkcompat could read:

             int
             checkcompat(to, e)
                 register ADDRESS *to;
                 register ENVELOPE *e;
             {
                 register STAB *s;

                 s = stab("private", ST_MAILER, ST_FIND);
                 if (s != NULL && e->e_from.q_mailer != LocalMailer &&
                     to->q_mailer == s->s_mailer)
                 {
                     usrerr("No private net mail allowed through this machine");
                     return (EX_UNAVAILABLE);
                 }
                 if (MsgSize > 50000 && bitnset(M_LOCALMAILER, to->q_mailer))
                 {
                     usrerr("Message too large for non-local delivery");
                     e->e_flags |= EF_NORETURN;
                     return (EX_UNAVAILABLE);
                 }
                 return (EX_OK);
             }

         This would reject messages greater than 50000 bytes
         unless they were local.  The EF_NORETURN  flag  can
         be  set in e->e_flags to suppress the return of the
         actual body of the message  in  the  error  return.
         The  actual use of this routine is highly dependent
         on the implementation, and use should be limited.
____________________
   [24]Actually, this is no longer true in SMTP; this infor-
mation is contained in the envelope.  The older ARPANET pro-
tocols did not completely distinguish envelope from header.











SMM:08-162         Sendmail Installation and Operation Guide


      6.3.3.  New Database Map Classes

              New key maps can be added by creating a  class
         initialization  function  and  a  lookup  function.
         These are then added to the routine setupmaps.

              The initialization function is called as

             xxx_map_init(MAP *map, char *args)

         The map is an internal data structure.  The args is
         a  pointer to the portion of the configuration file
         line following the map class name; flags and  file-
         names  can  be  extracted from this line.  The ini-
         tialization function must return true  if  it  suc-
         cessfully opened the map, false otherwise.

              The lookup function is called as

             xxx_map_lookup(MAP *map, char buf[], char **av, int *statp)

         The  map  defines  the map internally.  The buf has
         the input key.  This may be (and often is) used de-
         structively.   The av is a list of arguments passed
         in from the  rewrite  line.   The  lookup  function
         should  return  a pointer to the new value.  If the
         map lookup fails, *statp should be set to  an  exit
         status  code;  in  particular,  it should be set to
         EX_TEMPFAIL if recovery is to be attempted  by  the
         higher level code.

      6.3.4.  Queueing Function

              The routine shouldqueue is called to decide if
         a message should be  queued  or  processed  immedi-
         ately.   Typically this compares the message prior-
         ity to the current load average.  The default defi-
         nition is:

             bool
             shouldqueue(pri, ctime)
                 long pri;
                 time_t ctime;
             {
                 if (CurrentLA < QueueLA)
                     return false;
                 return (pri > (QueueFactor / (CurrentLA - QueueLA + 1)));
             }

         If  the  current load average (global variable Cur-
         rentLA,  which  is  set  before  this  function  is
         called) is less than the low threshold load average
         (option x, variable QueueLA),  shouldqueue  returns










Sendmail Installation and Operation Guide         SMM:08-163


         false  immediately  (that is, it should not queue).
         If  the  current  load  average  exceeds  the  high
         threshold  load  average  (option  X,  variable Re-
         fuseLA),  shouldqueue  returns  true   immediately.
         Otherwise,  it  computes  the function based on the
         message  priority,  the  queue  factor  (option  q,
         global  variable  QueueFactor), and the current and
         threshold load averages.

              An implementation wishing to take  the  actual
         age  of  the  message into account can also use the
         ctime parameter, which is the time that the message
         was first submitted to sendmail.  Note that the pri
         parameter is already  weighted  by  the  number  of
         times  the  message  has  been tried (although this
         tends to lower the priority  of  the  message  with
         time);  the  expectation is that the ctime would be
         used as an "escape clause" to ensure that  messages
         are eventually processed.

      6.3.5.  Refusing Incoming SMTP Connections

              The function refuseconnections returns true if
         incoming SMTP connections should be  refused.   The
         current  implementation is based exclusively on the
         current load average and the  refuse  load  average
         option (option X, global variable RefuseLA):

             bool
             refuseconnections()
             {
                 return (RefuseLA > 0 && CurrentLA >= RefuseLA);
             }

         A  more  clever  implementation  could look at more
         system resources.

      6.3.6.  Load Average Computation

              The routine getla returns the current load av-
         erage (as a rounded integer).  The distribution in-
         cludes several possible  implementations.   If  you
         are  porting  to  a new environment you may need to
         add some new tweaks.[25]




____________________
   [25]If you do,  please  send  updates  to  sendmail@Send-
mail.ORG.












SMM:08-164         Sendmail Installation and Operation Guide


   6.4.  Configuration in sendmail/daemon.c

           The  file  sendmail/daemon.c contains a number of
      routines that are dependent on  the  local  networking
      environment.   The  version  supplied assumes you have
      BSD style sockets.

           In previous releases,  we  recommended  that  you
      modify the routine maphostname if you wanted to gener-
      alize $[ ... $] lookups.  We now  recommend  that  you
      create a new keyed map instead.

   6.5.  LDAP

           In  this section we assume that sendmail has been
      compiled with support for LDAP.

      6.5.1.  LDAP Recursion

              LDAP Recursion allows you to add types to  the
         search  attributes  on  an  LDAP map specification.
         The syntax is:

         -v ATTRIBUTE[:TYPE[:OBJECTCLASS[|OBJECTCLASS|...]]]


              The new TYPEs are:

         NORMAL    This  attribute type specifies the attri-
                   bute to add to the results string.   This
                   is the default.

         DN        Any  matches  for  this attribute are ex-
                   pected to have a value of a fully  quali-
                   fied  distinguished  name.  sendmail will
                   lookup that DN and apply  the  attributes
                   requested to the returned DN record.

         FILTER    Any  matches  for  this attribute are ex-
                   pected to have a value of an LDAP  search
                   filter.   sendmail  will perform a lookup
                   with the same parameters as the  original
                   search  but  replaces  the  search filter
                   with the one specified here.

         URL       Any matches for this  attribute  are  ex-
                   pected  to  have  a value of an LDAP URL.
                   sendmail will perform a  lookup  of  that
                   URL  and  use  the  results  from the at-
                   tributes named in that URL.  Note however
                   that the search is done using the current
                   LDAP connection, regardless  of  what  is
                   specified  as  the scheme, LDAP host, and










Sendmail Installation and Operation Guide         SMM:08-165


                   LDAP port in the LDAP URL.

         Any untyped attributes are  considered  NORMAL  at-
         tributes as described above.

              The  optional  OBJECTCLASS  (| separated) list
         contains the objectClass values for which that  at-
         tribute  applies.  If the list is given, the attri-
         bute named will only be used if the LDAP record be-
         ing  returned  is  a  member  of that object class.
         Note that if these new value  attribute  TYPEs  are
         used  in  an AliasFile option setting, it will need
         to be double quoted to prevent sendmail  from  mis-
         parsing the colons.

              Note  that  LDAP recursion attributes which do
         not ultimately point to an LDAP record are not con-
         sidered an error.

         6.5.1.1.  Example

                 Since  examples  usually help clarify, here
            is an example which uses all  four  of  the  new
            types:

                O LDAPDefaultSpec=-h ldap.example.com -b dc=example,dc=com

                Kexample ldap
                         -z,
                         -k (&(objectClass=sendmailMTAAliasObject)(sendmailMTAKey=%0))
                         -v sendmailMTAAliasValue,mail:NORMAL:inetOrgPerson,
                            uniqueMember:DN:groupOfUniqueNames,
                            sendmailMTAAliasSearch:FILTER:sendmailMTAAliasObject,
                            sendmailMTAAliasURL:URL:sendmailMTAAliasObject


                 That definition specifies that:

             + Any  value  in a sendmailMTAAliasValue attri-
               bute will be added to the result  string  re-
               gardless of object class.
             + The  mail  attribute will be added to the re-
               sult string if the LDAP record is a member of
               the inetOrgPerson object class.
             + The uniqueMember attribute is a recursive at-
               tribute,  used  only  in   groupOfUniqueNames
               records, and should contain an LDAP DN point-
               ing to another LDAP record.  The desire  here
               is  to  return  the mail attribute from those
               DNs.
             + The  sendmailMTAAliasSearch   attribute   and
               sendmailMTAAliasURL  are  both  used  only if
               referenced in a sendmailMTAAliasObject.  They










SMM:08-166         Sendmail Installation and Operation Guide


               are  both recursive, the first for a new LDAP
               search string and the latter for an LDAP URL.

   6.6.  STARTTLS

           In this section we assume that sendmail has  been
      compiled  with  support for STARTTLS.  To properly un-
      derstand the use of STARTTLS in sendmail, it is neces-
      sary  to  understand  at least some basics about X.509
      certificates and public key cryptography.  This infor-
      mation  can  be found in books about SSL/TLS or on WWW
      sites, e.g., "http://www.OpenSSL.org/".

      6.6.1.  Certificates for STARTTLS

              When acting as  a  server,  sendmail  requires
         X.509 certificates to support STARTTLS: one as cer-
         tificate for the server (ServerCertFile and  corre-
         sponding  private  ServerKeyFile) at least one root
         CA (CACertFile), i.e., a certificate that  is  used
         to  sign other certificates, and a path to a direc-
         tory which contains (zero or more) other CAs  (CAC-
         ertPath).   The  file  specified via CACertFile can
         contain several certificates of CAs.   The  DNs  of
         these  certificates  are  sent to the client during
         the  TLS  handshake  (as  part  of   the   Certifi-
         cateRequest)  as  the list of acceptable CAs.  How-
         ever, do not list too many root CAs in  that  file,
         otherwise the TLS handshake may fail; e.g.,

             error:14094417:SSL routines:SSL3_READ_BYTES:
             sslv3 alert illegal parameter:s3_pkt.c:964:SSL alert number 47

         You  should probably put only the CA cert into that
         file that signed your own cert(s), or at least only
         those  you  trust.   The  CACertPath directory must
         contain the hashes of each CA certificate as  file-
         names (or as links to them).  Symbolic links can be
         generated with the  following  two  (Bourne)  shell
         commands:

             C=FileName_of_CA_Certificate
             ln -s $C `openssl x509 -noout -hash < $C`.0

         A better way to do this is to use the c_rehash com-
         mand that is part of the OpenSSL  distribution  be-
         cause  it handles subject hash collisions by incre-
         menting the number in the suffix of the filename of
         the  symbolic  link, e.g., .0 to .1, and so on.  An
         X.509 certificate is also required for  authentica-
         tion in client mode (ClientCertFile and correspond-
         ing private ClientKeyFile), however, sendmail  will
         always  use STARTTLS when offered by a server.  The










Sendmail Installation and Operation Guide         SMM:08-167


         client and server certificates  can  be  identical.
         Certificates can be obtained from a certificate au-
         thority or created with the help of  OpenSSL.   The
         required  format  for certificates and private keys
         is PEM.  To allow for automatic  startup  of  send-
         mail,  private  keys (ServerKeyFile, ClientKeyFile)
         must be stored unencrypted.  The keys are only pro-
         tected  by  the  permissions  of  the  file system.
         Never make a  private  key  available  to  a  third
         party.

              The   options  ClientCertFile,  ClientKeyFile,
         ServerCertFile, and ServerKeyFile can take a second
         file  name,  which must be separated from the first
         with a comma (note: do not use any spaces)  to  set
         up  a  second  cert/key  pair.  This can be used to
         have certs of different types, e.g., RSA and DSA.

      6.6.2.  PRNG for STARTTLS

              STARTTLS requires a strong pseudo random  num-
         ber  generator (PRNG) to operate properly.  Depend-
         ing on the TLS library you use, it may be  required
         to explicitly initialize the PRNG with random data.
         OpenSSL makes use of /dev/urandom(4)  if  available
         (this  corresponds  to  the  compile  flag HASURAN-
         DOMDEV).  On systems which  lack  this  support,  a
         random  file  must  be specified in the sendmail.cf
         file using the option RandFile.  It is strongly ad-
         vised  to  use  the  "Entropy Gathering Daemon" EGD
         from Brian Warner on those systems to provide  use-
         ful  random  data.   In this case, sendmail must be
         compiled with the flag EGD, and the RandFile option
         must   point   to   the  EGD  socket.   If  neither
         /dev/urandom(4) nor EGD are available, you have  to
         make  sure that useful random data is available all
         the time in RandFile.  If the file hasn't been mod-
         ified  in the last 10 minutes before it is supposed
         to be used by sendmail the  content  is  considered
         obsolete.  One method for generating this file is:

             openssl rand -out /etc/mail/randfile -rand /path/to/file:...256

         See the OpenSSL documentation for more information.
         In this case, the PRNG for TLS is only seeded  with
         other  random  data if the DontBlameSendmail option
         InsufficientEntropy is set.  This  is  most  likely
         not  sufficient  for certain actions, e.g., genera-
         tion of (temporary) keys.

              Please see the OpenSSL documentation or  other
         sources for further information about certificates,
         their creation and their usage, the importance of a










SMM:08-168         Sendmail Installation and Operation Guide


         good PRNG, and other aspects of TLS.

   6.7.  Encoding of STARTTLS and AUTH related Macros

           Macros  that  contain  STARTTLS  and AUTH related
      data which  comes  from  outside  sources,  e.g.,  all
      macros  containing  information from certificates, are
      encoded to avoid problems with non-printable  or  spe-
      cial  characters.   The latter are '\', '<', '>', '(',
      ')', '"', '+', and ' '.  All of these  characters  are
      replaced  by their value in hexadecimal with a leading
      '+'.  For example:

          /C=US/ST=California/O=endmail.org/OU=private/CN=Darth Mail (Cert)/
          Email=darth+cert@endmail.org

      is encoded as:

          /C=US/ST=California/O=endmail.org/OU=private/
          CN=Darth+20Mail+20+28Cert+29/Email=darth+2Bcert@endmail.org

      (line breaks have been inserted for readability).  The
      macros   which   are  subject  to  this  encoding  are
      {cert_subject}, {cert_issuer},  {cn_subject},  {cn_is-
      suer}, as well as {auth_authen} and {auth_author}.

7.  ACKNOWLEDGEMENTS

        I've worked on sendmail for many years, and many em-
   ployers have been remarkably  patient  about  letting  me
   work  on a large project that was not part of my official
   job.  This includes time on the  INGRES  Project  at  the
   University of California at Berkeley, at Britton Lee, and
   again on the Mammoth and Titan Projects at Berkeley.

        Much of the second wave of improvements resulting in
   version  8.1  should be credited to Bryan Costales of the
   International Computer Science Institute.  As  he  passed
   me drafts of his book on sendmail I was inspired to start
   working on things again.  Bryan  was  also  available  to
   bounce ideas off of.

        Gregory Neil Shapiro of Worcester Polytechnic Insti-
   tute has become instrumental in all  phases  of  sendmail
   support  and development, and was largely responsible for
   getting versions 8.8 and 8.9 out the door.

        Many, many people contributed  chunks  of  code  and
   ideas  to  sendmail.  It has proven to be a group network
   effort.  Version 8 in particular  was  a  group  project.
   The  following people and organizations made notable con-
   tributions:











Sendmail Installation and Operation Guide         SMM:08-169


       Claus Assmann
       John Beck, Hewlett-Packard & Sun Microsystems
       Keith Bostic, CSRG, University of California, Berkeley
       Andrew Cheng, Sun Microsystems
       Michael J. Corrigan, University of California, San Diego
       Bryan Costales, International Computer Science Institute & InfoBeat
       Par (Pell) Emanuelsson
       Craig Everhart, Transarc Corporation
       Per Hedeland, Ericsson
       Tom Ivar Helbekkmo, Norwegian School of Economics
       Kari Hurtta, Finnish Meteorological Institute
       Allan E. Johannesen, WPI
       Jonathan Kamens, OpenVision Technologies, Inc.
       Takahiro Kanbe, Fuji Xerox Information Systems Co., Ltd.
       Brian Kantor, University of California, San Diego
       John Kennedy, Cal State University, Chico
       Murray S. Kucherawy, HookUp Communication Corp.
       Bruce Lilly, Sony U.S.
       Karl London
       Motonori Nakamura, Ritsumeikan University & Kyoto University
       John Gardiner Myers, Carnegie Mellon University
       Neil Rickert, Northern Illinois University
       Gregory Neil Shapiro, WPI
       Eric Schnoebelen, Convex Computer Corp.
       Eric Wassenaar, National Institute for Nuclear and High Energy Physics, Amsterdam
       Randall Winchester, University of Maryland
       Christophe Wolfhugel, Pasteur Institute & Herve Schauer Consultants (Paris)
       Exactis.com, Inc.

   I apologize for anyone I have omitted, misspelled, misat-
   tributed,  or otherwise missed.  At this point, I suspect
   that at least a hundred people have contributed code, and
   many  more  have contributed ideas, comments, and encour-
   agement.  I've tried to list them in the RELEASE_NOTES in
   the distribution directory.  I appreciate their contribu-
   tion as well.

        Special thanks are reserved for Michael Corrigan and
   Christophe  Wolfhugel, who besides being wonderful guinea
   pigs and contributors have also consented to be added  to
   the  ``sendmail@Sendmail.ORG'' list and, by answering the
   bulk of the questions sent to that list, have freed me up
   to do other work.























                          APPENDIX  A


                      COMMAND LINE FLAGS




     Arguments  must  be  presented  with  flags  before ad-
dresses.  The flags are:

-Ax       Select an alternative .cf  file  which  is  either
          sendmail.cf  for -Am or submit.cf for -Ac.  By de-
          fault the .cf file is chosen based on  the  opera-
          tion  mode.   For -bm (default), -bs, and -t it is
          submit.cf if it exists, for all others it is send-
          mail.cf.

-bx       Set operation mode to x.  Operation modes are:

              m   Deliver mail (default)
              s   Speak SMTP on input side
              a*  ``Arpanet'' mode (get envelope sender information from header)
              C   Check the configuration file
              d   Run as a daemon in background
              D   Run as a daemon in foreground
              t   Run in test mode
              v   Just verify addresses, don't collect or deliver
              i   Initialize the alias database
              p   Print the mail queue
              P   Print overview over the mail queue (requires shared memory)
              h   Print the persistent host status database
              H   Purge expired entries from the persistent host status database


-Btype    Indicate body type.

-Cfile    Use a different configuration file.  Sendmail runs
          as the invoking user (rather than root) when  this
          flag is specified.

-D logfile
          Send debugging output to the indicated logfile in-
          stead of stdout.

-dlevel   Set debugging level.

-f addr   The envelope sender address is set to addr.   This
          address  may  also  be used in the From: header if
____________________
   *Deprecated.




SMM:08-170         Sendmail Installation and Operation Guide







Sendmail Installation and Operation Guide         SMM:08-171


          that header is missing during initial  submission.
          The envelope sender address is used as the recipi-
          ent for delivery status notifications and may also
          appear in a Return-Path: header.

-F name   Sets the full name of this user to name.

-G        When  accepting messages via the command line, in-
          dicate that they are for relay  (gateway)  submis-
          sion.   sendmail  may complain about syntactically
          invalid messages, e.g.,  unqualified  host  names,
          rather  than  fixing  them  when this flag is set.
          sendmail will not do any canonicalization in  this
          mode.

-h cnt    Sets  the "hop count" to cnt.  This represents the
          number of times this message has been processed by
          sendmail  (to  the  extent that it is supported by
          the underlying networks).  Cnt is incremented dur-
          ing  processing,  and  if  it reaches MAXHOP (cur-
          rently 25) sendmail throws away the  message  with
          an error.

-L tag    Sets  the  identifier  used for syslog.  Note that
          this identifier is set as early as possible.  How-
          ever,  sendmail  may be used if problems arise be-
          fore the command line arguments are processed.

-n        Don't do aliasing or forwarding.

-N notifications
          Tag all addresses being sent as wanting the  indi-
          cated  notifications,  which  consists of the word
          "NEVER" or a comma-separated  list  of  "SUCCESS",
          "FAILURE",  and  "DELAY"  for successful delivery,
          failure, and a message that is stuck  in  a  queue
          somewhere.  The default is "FAILURE,DELAY".

-r addr   An obsolete form of -f.

-oxvalue  Set  option  x  to the specified value.  These op-
          tions are described in Section 5.6.

-Ooption=value
          Set option to the specified value (for  long  form
          option  names).   These  options  are described in
          Section 5.6.

-Mxvalue  Set macro x to the specified value.

-pprotocol
          Set the sending protocol.  Programs are encouraged
          to  set  this.   The  protocol field can be in the










SMM:08-172         Sendmail Installation and Operation Guide


          form protocol:host to set both the sending  proto-
          col and sending host.  For example, "-pUUCP:uunet"
          sets the sending protocol to UUCP and the  sending
          host to uunet.  (Some existing programs use -oM to
          set the r and s macros; this is equivalent to  us-
          ing -p.)

-qtime    Try to process the queued up mail.  If the time is
          given, a sendmail will start one or more processes
          to  run through the queue(s) at the specified time
          interval to deliver  queued  mail;  otherwise,  it
          only runs once.  Each of these processes acts on a
          workgroup.  These  processes  are  also  known  as
          workgroup  processes  or  WGP's  for  short.  Each
          workgroup is responsible for controlling the  pro-
          cessing  of  one  or  more queues; workgroups help
          manage the use of system  resources  by  sendmail.
          Each  workgroup may have one or more children con-
          currently processing queues depending on the  set-
          ting of MaxQueueChildren.

-qptime   Similar  to  -q  with a time argument, except that
          instead of periodically  starting  WGP's  sendmail
          starts  persistent  WGP's  that  alternate between
          processing queues and sleeping.  The sleep time is
          specified  by  the time argument; it defaults to 1
          second, except that a WGP always sleeps at least 5
          seconds if their queues were empty in the previous
          run.  Persistent processes are managed by a  queue
          control  process  (QCP).   The  QCP  is the parent
          process of the WGP's.  Typically the QCP  will  be
          the sendmail daemon (when started with -bd or -bD)
          or a special process (named Queue  control)  (when
          started  without -bd or -bD).  If a persistent WGP
          ceases to be active for some  reason  another  WGP
          will  be started by the QCP for the same workgroup
          in most cases. When  a  persistent  WGP  has  core
          dumped,  the  debug  flag no_persistent_restart is
          set  or  the  specific  persistent  WGP  has  been
          restarted too many times already then the WGP will
          not be started again and a message will be  logged
          to  this  effect.   To  stop  (SIGTERM) or restart
          (SIGHUP) persistent WGP's the  appropriate  signal
          should  be sent to the QCP. The QCP will propagate
          the signal to all of the WGP's and if  appropriate
          restart the persistent WGP's.

-qGname   Run the jobs in the queue group name once.

-q[!]Xstring
          Run  the  queue  once,  limiting the jobs to those
          matching Xstring.  The key letter X can  be  I  to
          limit  based on queue identifier, R to limit based










Sendmail Installation and Operation Guide         SMM:08-173


          on recipient, S to limit based on sender, or Q  to
          limit  based  on quarantine reason for quarantined
          jobs.  A particular queued job is accepted if  one
          of the corresponding attributes contains the indi-
          cated string.  The optional  !  character  negates
          the condition tested.  Multiple -qX flags are per-
          mitted,  with  items  with  the  same  key  letter
          "or'ed"  together,  and  items  with different key
          letters "and'ed" together.

-Q[reason]
          Quarantine a normal queue  items  with  the  given
          reason  or unquarantine quarantined queue items if
          no reason is given.  This should only be used with
          some  sort  of item matching using -q[!]Xstring as
          described above.

-R ret    What information you want returned if the  message
          bounces;  ret  can  be  "HDRS" for headers only or
          "FULL" for headers plus body.  This is  a  request
          only;  the  other end is not required to honor the
          parameter.  If "HDRS" is specified  local  bounces
          also return only the headers.

-t        Read  the  header  for  "To:",  "Cc:",  and "Bcc:"
          lines, and send to everyone listed in those lists.
          The  "Bcc:"  line  will be deleted before sending.
          Any addresses  in  the  argument  vector  will  be
          deleted from the send list.

-V envid  The indicated envid is passed with the envelope of
          the message and returned if the message bounces.

-X logfile
          Log all traffic in and out of sendmail in the  in-
          dicated  logfile  for  debugging  mailer problems.
          This produces a  lot  of  data  very  quickly  and
          should be used sparingly.

     There  are a number of options that may be specified as
primitive flags.  These are the e,  i,  m,  and  v  options.
Also, the f option may be specified as the -s flag.  The DSN
related options "-N", "-R", and  "-V"  have  no  effects  on
sendmail running as daemon.






















                        APPENDIX  B


                     QUEUE FILE FORMATS




     This  appendix describes the format of the queue files.
These files live in a queue directory.  The  individual  qf,
hf, Qf, df, and xf files may be stored in separate qf/, df/,
and xf/ subdirectories if they are present in the queue  di-
rectory.

     All  queue  files  have  the name ttYMDhmsNNppppp where
YMDhmsNNppppp is the id for this message and  the  tt  is  a
type.  The individual letters in the id are:

Y    Encoded year

M    Encoded month

D    Encoded day

h    Encoded hour

m    Encoded minute

s    Encoded second

NN   Encoded envelope number

ppppp
     At least five decimal digits of the process ID

     All files with the same id collectively define one mes-
sage.  Due to the use  of  memory-buffered  files,  some  of
these files may never appear on disk.

     The types are:

qf   The  queue control file.  This file contains the infor-
     mation necessary to process the job.

hf   The same as a queue control file, but for a quarantined
     queue job.

df   The data file.  The message body (excluding the header)
     is kept in this file.  Sometimes the  df  file  is  not
     stored  in  the  same directory as the qf file; in this
     case, the qf file contains a `d' record which names the
     queue directory that contains the df file.



SMM:08-174         Sendmail Installation and Operation Guide







Sendmail Installation and Operation Guide         SMM:08-175


tf   A temporary file.  This is an image of the qf file when
     it is being rebuilt.  It should be renamed to a qf file
     very quickly.

xf   A  transcript  file, existing during the life of a ses-
     sion showing everything that happens during  that  ses-
     sion.  Sometimes the xf file must be generated before a
     queue group has been selected; in  this  case,  the  xf
     file will be stored in a directory of the default queue
     group.

Qf   A ``lost'' queue control file.  sendmail renames  a  qf
     file to Qf if there is a severe (configuration) problem
     that  cannot  be  solved  without  human  intervention.
     Search  the logfile for the queue file id to figure out
     what happened.  After you resolved the problem, you can
     rename the Qf file to qf and send it again.

     The  queue  control  file  is structured as a series of
lines each beginning with a code letter.  The lines  are  as
follows:

V    The  version  number  of the queue file format, used to
     allow new sendmail binaries to read queue files created
     by  older versions.  Defaults to version zero.  Must be
     the first line of the file if present.   For  8.12  the
     version number is 6.

A    The  information  given  by  the AUTH= parameter of the
     "MAIL FROM:" command or  $f@$j  if  sendmail  has  been
     called directly.

H    A  header definition.  There may be any number of these
     lines.  The order is important: they represent the  or-
     der in the final message.  These use the same syntax as
     header definitions in the configuration file.

C    The  controlling   address.    The   syntax   is   "lo-
     caluser:aliasname".  Recipient addresses following this
     line will be flagged so that deliveries will be run  as
     the  localuser (a user name from the /etc/passwd file);
     aliasname is the name of the  alias  that  expanded  to
     this address (used for printing messages).

q    The quarantine reason for quarantined queue items.

Q    The  ``original  recipient'',  specified  by the ORCPT=
     field in an ESMTP transaction.   Used  exclusively  for
     Delivery  Status Notifications.  It applies only to the
     following `R' line.

r    The ``final recipient'' used for Delivery Status  Noti-
     fications.  It applies only to the following `R' line.










SMM:08-176         Sendmail Installation and Operation Guide


R    A  recipient address.  This will normally be completely
     aliased, but is actually realiased when the job is pro-
     cessed.   There  will  be  one line for each recipient.
     Version 1 qf files also include a leading  colon-termi-
     nated  list of flags, which can be `S' to return a mes-
     sage on successful final delivery, `F' to return a mes-
     sage on failure, `D' to return a message if the message
     is delayed, `B' to indicate that the body should be re-
     turned,  `N' to suppress returning the body, and `P' to
     declare this as a ``primary'' (command  line  or  SMTP-
     session) address.

S    The  sender  address.   There  may only be one of these
     lines.

T    The job creation time.  This is used to compute when to
     time out the job.

P    The  current  message  priority.  This is used to order
     the queue.  Higher numbers mean lower priorities.   The
     priority changes as the message sits in the queue.  The
     initial priority depends on the message class  and  the
     size of the message.

M    A  message.  This line is printed by the mailq command,
     and is generally used to store status information.   It
     can contain any text.

F    Flag bits, represented as one letter per flag.  Defined
     flag bits are r indicating that this is a response mes-
     sage  and  w indicating that a warning message has been
     sent announcing that the mail has been delayed.   Other
     flag  bits  are:  8:  the body contains 8bit data, b: a
     Bcc: header should be removed, d: the mail has RET  pa-
     rameters  (see  RFC  1894),  n: the body of the message
     should not be returned in case of an error, s: the  en-
     velope has been split.

N    The total number of delivery attempts.

K    The time (as seconds since January 1, 1970) of the last
     delivery attempt.

d    If the df file is in a different directory than the  qf
     file,  then a `d' record is present, specifying the di-
     rectory in which the df file resides.

I    The i-number of the data file; this can be used to  re-
     cover your mail queue after a disastrous disk crash.

$    A  macro  definition.  The values of certain macros are
     passed through to the queue run phase.











Sendmail Installation and Operation Guide         SMM:08-177


B    The body type.  The remainder of the  line  is  a  text
     string  defining the body type.  If this field is miss-
     ing, the body type is assumed to be "undefined" and  no
     special  processing  is  attempted.   Legal  values are
     "7BIT" and "8BITMIME".

Z    The original envelope id (from the ESMTP  transaction).
     For Deliver Status Notifications only.

     As  an  example,  the following is a queue file sent to
"eric@mammoth.Berkeley.EDU"  and   "bostic@okeeffe.CS.Berke-
ley.EDU"[1]:

    V4
    T711358135
    K904446490
    N0
    P2100941
    $_eric@localhost
    ${daemon_flags}
    Seric
    Ceric:100:1000:sendmail@vangogh.CS.Berkeley.EDU
    RPFD:eric@mammoth.Berkeley.EDU
    RPFD:bostic@okeeffe.CS.Berkeley.EDU
    H?P?Return-path: <^g>
    H??Received: by vangogh.CS.Berkeley.EDU (5.108/2.7) id AAA06703;
        Fri, 17 Jul 1992 00:28:55 -0700
    H??Received: from mail.CS.Berkeley.EDU by vangogh.CS.Berkeley.EDU (5.108/2.7)
        id AAA06698; Fri, 17 Jul 1992 00:28:54 -0700
    H??Received: from [128.32.31.21] by mail.CS.Berkeley.EDU (5.96/2.5)
        id AA22777; Fri, 17 Jul 1992 03:29:14 -0400
    H??Received: by foo.bar.baz.de (5.57/Ultrix3.0-C)
        id AA22757; Fri, 17 Jul 1992 09:31:25 GMT
    H?F?From: eric@foo.bar.baz.de (Eric Allman)
    H?x?Full-name: Eric Allman
    H??Message-id: <9207170931.AA22757@foo.bar.baz.de>
    H??To: sendmail@vangogh.CS.Berkeley.EDU
    H??Subject: this is an example message

This  shows  the person who sent the message, the submission
time (in seconds since January 1, 1970), the message  prior-
ity,  the message class, the recipients, and the headers for
the message.




____________________
   [1]This  example is contrived and probably inaccurate for
your environment.  Glance over it to get  an  idea;  nothing
can replace looking at what your own system generates.















                        APPENDIX  C


                  SUMMARY OF SUPPORT FILES




     This is a summary of the support  files  that  sendmail
creates or generates.  Many of these can be changed by edit-
ing the sendmail.cf file; check there  to  find  the  actual
pathnames.

/usr/sbin/sendmail
          The binary of sendmail.

/usr/bin/newaliases
          A  link  to  /usr/sbin/sendmail;  causes the alias
          database to be rebuilt.  Running this  program  is
          completely  equivalent  to giving sendmail the -bi
          flag.

/usr/bin/mailq
          Prints a listing of the mail queue.  This  program
          is equivalent to using the -bp flag to sendmail.

/etc/mail/sendmail.cf
          The configuration file, in textual form.

/etc/mail/helpfile
          The SMTP help file.

/etc/mail/statistics
          A statistics file; need not be present.

/etc/mail/sendmail.pid
          Created in daemon mode; it contains the process id
          of the current SMTP daemon.  If you  use  this  in
          scripts;  use  ``head  -1''  to get just the first
          line; the second line contains  the  command  line
          used  to  invoke the daemon, and later versions of
          sendmail may add more  information  to  subsequent
          lines.

/etc/mail/aliases
          The textual version of the alias file.

/etc/mail/aliases.db
          The alias file in hash(3) format.

/etc/mail/aliases.{pag,dir}
          The alias file in ndbm(3) format.



SMM:08-178         Sendmail Installation and Operation Guide







Sendmail Installation and Operation Guide         SMM:08-179


/var/spool/mqueue
          The  directory in which the mail queue(s) and tem-
          porary files reside.

/var/spool/mqueue/qf*
          Control (queue) files for messages.

/var/spool/mqueue/df*
          Data files.

/var/spool/mqueue/tf*
          Temporary versions of the qf  files,  used  during
          queue file rebuild.

/var/spool/mqueue/xf*
          A transcript of the current session.















































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Sendmail Installation and Operation Guide           SMM:08-3


                          TABLE OF CONTENTS

1.  BASIC INSTALLATION ................................    7
   1.1.  Compiling Sendmail ...........................    7
      1.1.1.  Tweaking the Build Invocation ...........    7
      1.1.2.  Creating a Site Configuration File ......    8
      1.1.3.  Tweaking the Makefile ...................    8
      1.1.4.  Compilation and installation ............    9
   1.2.  Configuration Files ..........................   10
   1.3.  Details of Installation Files ................   12
      1.3.1.  /usr/sbin/sendmail ......................   12
      1.3.2.  /etc/mail/sendmail.cf ...................   12
      1.3.3.  /etc/mail/submit.cf .....................   13
      1.3.4.  /usr/bin/newaliases .....................   13
      1.3.5.  /usr/bin/hoststat .......................   13
      1.3.6.  /usr/bin/purgestat ......................   13
      1.3.7.  /var/spool/mqueue .......................   14
      1.3.8.  /var/spool/clientmqueue .................   14
      1.3.9.  /var/spool/mqueue/.hoststat .............   15
      1.3.10.  /etc/mail/aliases* .....................   15
      1.3.11.  /etc/rc or /etc/init.d/sendmail ........   15
      1.3.12.  /etc/mail/helpfile .....................   16
      1.3.13.  /etc/mail/statistics ...................   16
      1.3.14.  /usr/bin/mailq .........................   16
      1.3.15.  sendmail.pid ...........................   18
      1.3.16.  Map Files ..............................   18
2.  NORMAL OPERATIONS .................................   19
   2.1.  The System Log ...............................   19
      2.1.1.  Format ..................................   19
      2.1.2.  Levels ..................................   20
   2.2.  Dumping State ................................   21
   2.3.  The Mail Queues ..............................   21
      2.3.1.  Queue Groups and Queue Directories ......   21
      2.3.2.  Queue Runs ..............................   22
      2.3.3.  Manual Intervention .....................   23
      2.3.4.  Printing the queue ......................   23
      2.3.5.  Forcing the queue .......................   24
      2.3.6.  Quarantined Queue Items .................   25
   2.4.  Disk Based Connection Information ............   26
   2.5.  The Service Switch ...........................   27
   2.6.  The Alias Database ...........................   28
      2.6.1.  Rebuilding the alias database ...........   30
      2.6.2.  Potential problems ......................   30
      2.6.3.  List owners .............................   31
   2.7.  User Information Database ....................   31
   2.8.  Per-User Forwarding (.forward Files) .........   31
   2.9.  Special Header Lines .........................   32
      2.9.1.  Errors-To: ..............................   32
      2.9.2.  Apparently-To: ..........................   32
      2.9.3.  Precedence ..............................   33
   2.10.  IDENT Protocol Support ......................   33
3.  ARGUMENTS .........................................   34
   3.1.  Queue Interval ...............................   34










SMM:08-4           Sendmail Installation and Operation Guide


   3.2.  Daemon Mode ..................................   35
   3.3.  Forcing the Queue ............................   35
   3.4.  Debugging ....................................   36
   3.5.  Changing the Values of Options ...............   37
   3.6.  Trying a Different Configuration File ........   37
   3.7.  Logging Traffic ..............................   38
   3.8.  Testing Configuration Files ..................   38
   3.9.  Persistent Host Status Information ...........   40
4.  TUNING ............................................   40
   4.1.  Timeouts .....................................   41
      4.1.1.  Queue interval ..........................   41
      4.1.2.  Read timeouts ...........................   41
      4.1.3.  Message timeouts ........................   44
   4.2.  Forking During Queue Runs ....................   45
   4.3.  Queue Priorities .............................   46
   4.4.  Load Limiting ................................   46
   4.5.  Resource Limits ..............................   47
   4.6.   Measures against Denial of Service Attacks
      .................................................   47
   4.7.  Delivery Mode ................................   48
   4.8.  Log Level ....................................   49
   4.9.  File Modes ...................................   50
      4.9.1.  To suid or not to suid?  ................   50
      4.9.2.  Turning off security checks .............   51
   4.10.  Connection Caching ..........................   54
   4.11.  Name Server Access ..........................   55
   4.12.  Moving the Per-User Forward Files ...........   57
   4.13.  Free Space ..................................   57
   4.14.  Maximum Message Size ........................   58
   4.15.  Privacy Flags ...............................   58
   4.16.  Send to Me Too ..............................   58
5.  THE WHOLE SCOOP ON THE CONFIGURATION FILE .........   58
   5.1.  R and S -- Rewriting Rules ...................   59
      5.1.1.  The left hand side ......................   60
      5.1.2.  The right hand side .....................   60
      5.1.3.  Semantics of rewriting rule sets ........   63
      5.1.4.  Ruleset hooks ...........................   64
         5.1.4.1.  check_relay ........................   65
         5.1.4.2.  check_mail .........................   65
         5.1.4.3.  check_rcpt .........................   65
         5.1.4.4.  check_data .........................   65
         5.1.4.5.  check_compat .......................   65
         5.1.4.6.  check_eoh ..........................   66
         5.1.4.7.  check_eom ..........................   66
         5.1.4.8.  check_etrn .........................   66
         5.1.4.9.  check_expn .........................   67
         5.1.4.10.  check_vrfy ........................   67
         5.1.4.11.  trust_auth ........................   67
         5.1.4.12.  tls_client ........................   67
         5.1.4.13.  tls_server ........................   67
         5.1.4.14.  tls_rcpt ..........................   67
         5.1.4.15.  srv_features ......................   68
         5.1.4.16.  try_tls ...........................   69










Sendmail Installation and Operation Guide           SMM:08-5


         5.1.4.17.        tls_srv_features       and
            tls_clt_features
                 ......................................   69
         5.1.4.18.  authinfo ..........................   70
         5.1.4.19.  queuegroup ........................   71
         5.1.4.20.  greet_pause .......................   71
      5.1.5.  IPC mailers .............................   72
   5.2.  D -- Define Macro ............................   72
   5.3.  C and F -- Define Classes ....................   84
   5.4.  M -- Define Mailer ...........................   86
   5.5.  H -- Define Header ...........................   95
   5.6.  O -- Set Option ..............................   96
   5.7.  P -- Precedence Definitions ..................  129
   5.8.  V -- Configuration Version Level .............  130
   5.9.  K -- Key File Declaration ....................  132
   5.10.  Q -- Queue Group Declaration ................  145
   5.11.  X -- Mail Filter (Milter) Definitions .......  147
   5.12.  The User Database ...........................  148
      5.12.1.  Structure of the user database .........  149
      5.12.2.  User database semantics ................  150
      5.12.3.  Creating the database[23] ..............  151
6.  OTHER CONFIGURATION ...............................  151
   6.1.  Parameters in devtools/OS/$oscf ..............  151
      6.1.1.  For Future Releases .....................  153
   6.2.  Parameters in sendmail/conf.h ................  153
   6.3.  Configuration in sendmail/conf.c .............  158
      6.3.1.  Built-in Header Semantics ...............  158
      6.3.2.  Restricting Use of Email ................  161
      6.3.3.  New Database Map Classes ................  162
      6.3.4.  Queueing Function .......................  162
      6.3.5.  Refusing Incoming SMTP Connections ......  163
      6.3.6.  Load Average Computation ................  163
   6.4.  Configuration in sendmail/daemon.c ...........  164
   6.5.  LDAP .........................................  164
      6.5.1.  LDAP Recursion ..........................  164
         6.5.1.1.  Example ............................  165
   6.6.  STARTTLS .....................................  166
      6.6.1.  Certificates for STARTTLS ...............  166
      6.6.2.  PRNG for STARTTLS .......................  167
   6.7.   Encoding  of  STARTTLS  and  AUTH  related
      Macros ..........................................  168
7.  ACKNOWLEDGEMENTS ..................................  168
Appendix A.  COMMAND LINE FLAGS .......................  170
Appendix B.  QUEUE FILE FORMATS .......................  174
Appendix C.  SUMMARY OF SUPPORT FILES .................  178


















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