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MASTER(5)                     File Formats Manual                    MASTER(5)

       master - Postfix master process configuration file format

       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

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

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

       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.

       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.

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

       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

       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 "[]",
                     but this form is not necessary.

                     Examples: a  service  named  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

                     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 systems the  unix  type  is  implemented  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, receives one
                     open  connection (file descriptor passing) per connection
                     request, and is accessible to 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).

                     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

       Chroot (default: 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

       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 single-
              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-

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

              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
                     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:  do  not  specify  whitespace around the "=". In
                     parameter values, either avoid whitespace altogether, use
                     commas  instead of spaces, or consider overrides like "-o
                     name=$override_parameter" with $override_parameter set in

                     NOTE 2: 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

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

       Use  "postconf readme_directory" or "postconf html_directory" to locate
       this information.
       BASIC_CONFIGURATION_README, basic configuration
       DEBUG_README, Postfix debugging

       The Secure Mailer license must be distributed with this software.

       Initial version by
       Magnus Baeck
       Lund Institute of Technology

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