Postfix manual - master(5)

    MASTER(5)                                                            MASTER(5)

    NAME
           master - Postfix master process configuration file format

    DESCRIPTION
           The  Postfix  mail  system  is  implemented by small number of (mostly)
           client commands that are invoked by users, and by a  larger  number  of
           services that run in the background.

           Postfix  services are implemented by daemon processes. These run in the
           background under control of the master(8) process.  The master.cf  con-
           figuration file defines how a client program connects to a service, and
           what daemon program runs when a service is requested.  Most daemon pro-
           cesses  are short-lived and terminate voluntarily after serving max_use
           clients, or after inactivity for max_idle or more units of time.

           All daemons specified here must speak a Postfix-internal  protocol.  In
           order  to  execute  non-Postfix  software  use the local(8), pipe(8) or
           spawn(8) services, or run the  server  under  control  by  inetd(8)  or
           equivalent.

           After  changing  master.cf  you must execute "postfix reload" to reload
           the configuration.

    SYNTAX
           The general format of the master.cf file is as follows:

           o      Empty lines and whitespace-only lines are ignored, as are  lines
                  whose first non-whitespace character is a `#'.

           o      A  logical  line  starts  with  non-whitespace text. A line that
                  starts with whitespace continues a logical line.

           o      Each logical line defines a single Postfix service.   Each  ser-
                  vice  is  identified  by  its  name and type as described below.
                  When multiple lines specify the same service name and type, only
                  the  last  one is remembered.  Otherwise, the order of master.cf
                  service definitions does not matter.

           Each logical line consists of eight  fields  separated  by  whitespace.
           These  are described below in the order as they appear in the master.cf
           file.

           Where applicable a field of "-"  requests  that  the  built-in  default
           value  be  used.  For boolean fields specify "y" or "n" to override the
           default value.

           Service name
                  The service name syntax depends on the service type as described
                  next.

           Service type
                  Specify one of the following service types:

                  inet   The  service listens on a TCP/IP socket and is accessible
                         via the network.

                         The service name is specified as host:port, denoting  the
                         host   and  port  on  which  new  connections  should  be
                         accepted. The host  part  (and  colon)  may  be  omitted.
                         Either  host  or port may be given in symbolic form (host
                         or service name) or in numeric form (IP address  or  port
                         number).   Host  information may be enclosed inside "[]";
                         this form is necessary only with IPv6 addresses.

                         Examples: a  service  named  127.0.0.1:smtp  or  ::1:smtp
                         receives mail via the loopback interface only; and a ser-
                         vice named 10025 accepts connections on  TCP  port  10025
                         via  all  interfaces  configured with the inet_interfaces
                         parameter.

                         Note:  with  Postfix  version  2.2  and   later   specify
                         "inet_interfaces  = loopback-only" in main.cf, instead of
                         hard-coding loopback IP address information in  master.cf
                         or in main.cf.

                  unix   The service listens on a UNIX-domain socket and is acces-
                         sible for local clients only.

                         The service name is a pathname relative  to  the  Postfix
                         queue    directory    (pathname   controlled   with   the
                         queue_directory configuration parameter in main.cf).

                         On Solaris 8 and earlier systems the unix type is  imple-
                         mented with streams sockets.

                  fifo   The  service listens on a FIFO (named pipe) and is acces-
                         sible for local clients only.

                         The service name is a pathname relative  to  the  Postfix
                         queue    directory    (pathname   controlled   with   the
                         queue_directory configuration parameter in main.cf).

                  pass   The service listens  on  a  UNIX-domain  socket,  and  is
                         accessible  to  local  clients only. It receives one open
                         connection  (file  descriptor  passing)  per   connection
                         request.

                         The  service  name  is a pathname relative to the Postfix
                         queue   directory   (pathname   controlled    with    the
                         queue_directory configuration parameter in main.cf).

                         On  Solaris 8 and earlier systems the pass type is imple-
                         mented with streams sockets.

                         This feature is available as of Postfix version 2.5.

           Private (default: y)
                  Whether or not access is restricted to the mail system.   Inter-
                  net (type inet) services can't be private.

           Unprivileged (default: y)
                  Whether the service runs with root privileges or as the owner of
                  the  Postfix  system  (the  owner  name  is  controlled  by  the
                  mail_owner configuration variable in the main.cf file).

                  The  local(8), pipe(8), spawn(8), and virtual(8) daemons require
                  privileges.

           Chroot (default: Postfix >= 3.0: n, Postfix <3.0: y)
                  Whether or not the service  runs  chrooted  to  the  mail  queue
                  directory (pathname is controlled by the queue_directory config-
                  uration variable in the main.cf file).

                  Chroot should not be used with the local(8), pipe(8),  spawn(8),
                  and virtual(8) daemons.  Although the proxymap(8) server can run
                  chrooted, doing so defeats most of the purpose  of  having  that
                  service in the first place.

                  The files in the examples/chroot-setup subdirectory of the Post-
                  fix source archive show set up a Postfix chroot environment on a
                  variety  of  systems.  See  also  BASIC_CONFIGURATION_README for
                  issues related to running daemons chrooted.

           Wake up time (default: 0)
                  Automatically wake up the named service after the specified num-
                  ber  of seconds. The wake up is implemented by connecting to the
                  service and sending a wake up request.  A ? at the  end  of  the
                  wake-up  time  field  requests  that  no  wake up events be sent
                  before the first time a service is used.  Specify 0 for no auto-
                  matic wake up.

                  The  pickup(8),  qmgr(8)  and flush(8) daemons require a wake up
                  timer.

           Process limit (default: $default_process_limit)
                  The maximum number of processes that may  execute  this  service
                  simultaneously. Specify 0 for no process count limit.

                  NOTE:  Some  Postfix  services  must  be  configured  as  a sin-
                  gle-process service (for example,  qmgr(8))  and  some  services
                  must   be   configured  with  no  process  limit  (for  example,
                  cleanup(8)).  These limits must not be changed.

           Command name + arguments
                  The command to be executed.  Characters that are special to  the
                  shell  such  as  ">"  or  "|"  have no special meaning here, and
                  quotes cannot be used to  protect  arguments  containing  white-
                  space.  To  protect  whitespace,  use  "{"  and "}" as described
                  below.

                  The command name is relative to  the  Postfix  daemon  directory
                  (pathname  is  controlled  by the daemon_directory configuration
                  variable).

                  The command argument syntax for specific commands  is  specified
                  in the respective daemon manual page.

                  The  following command-line options have the same effect for all
                  daemon programs:

                  -D     Run the daemon under control  by  the  command  specified
                         with the debugger_command variable in the main.cf config-
                         uration file.  See DEBUG_README for hints and tips.

                  -o { name = value } (long form, Postfix >= 3.0)

                  -o name=value (short form)
                         Override the named main.cf configuration  parameter.  The
                         parameter  value  can  refer to other parameters as $name
                         etc., just like in main.cf.  See postconf(5) for  syntax.

                         NOTE  1:  With  the  "long  form" shown above, whitespace
                         after "{", around "=", and before  "}"  is  ignored,  and
                         whitespace within the parameter value is preserved.

                         NOTE 2: with the "short form" shown above, do not specify
                         whitespace around the "="  or  in  parameter  values.  To
                         specify  a  parameter value that contains whitespace, use
                         the long form described above, or use commas  instead  of
                         spaces, or specify the value in main.cf. Example:

                         /etc/postfix/master.cf:
                             submission inet .... smtpd
                                 -o smtpd_xxx_yyy=$submission_xxx_yyy

                         /etc/postfix/main.cf
                             submission_xxx_yyy = text with whitespace...

                         NOTE 3: Over-zealous use of parameter overrides makes the
                         Postfix configuration hard to  understand  and  maintain.
                         At  a certain point, it might be easier to configure mul-
                         tiple instances of Postfix, instead of configuring multi-
                         ple personalities via master.cf.

                  -v     Increase  the  verbose logging level. Specify multiple -v
                         options to make a  Postfix  daemon  process  increasingly
                         verbose.

                  Other command-line arguments
                         Specify "{" and "}" around command arguments that contain
                         whitespace (Postfix 3.0 and later). Whitespace after  "{"
                         and before "}" is ignored.

    SEE ALSO
           master(8), process manager
           postconf(5), configuration parameters

    README FILES
           BASIC_CONFIGURATION_README, basic configuration
           DEBUG_README, Postfix debugging

    LICENSE
           The Secure Mailer license must be distributed with this software.

    AUTHOR(S)
           Initial version by
           Magnus Baeck
           Lund Institute of Technology
           Sweden

           Wietse Venema
           IBM T.J. Watson Research
           P.O. Box 704
           Yorktown Heights, NY 10598, USA

           Wietse Venema
           Google, Inc.
           111 8th Avenue
           New York, NY 10011, USA

                                                                         MASTER(5)