MASTER(5)                                                            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, started on-demand by the master(8) process.  The
       configuration  file defines how a client program connects to a service,
       and what daemon program runs when a service is requested.  Most  daemon
       processes  are  short-lived  and  terminate  voluntarily  after serving
       max_use clients, or after inactivity for  max_idle  or  more  units  of

       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 execute the software with inetd(8) or equivalent.

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

       The general format of the 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
              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

       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  (see
                     hosts(5)  or  services(5)) 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  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, instead  of
                     hard-coding  loopback IP address information in
                     or in

              unix   The service listens on a UNIX-domain stream socket and is
                     accessible 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

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

                     The service listens on a UNIX-domain datagram socket  and
                     is accessible 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

              fifo (obsolete)
                     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

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

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

                     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 a service is internal to Postfix (pathname  starts  with
              private/),  or exposed through Postfix command-line tools (path-
              name starts with public/).  Internet (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 file).

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

       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 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 show how to 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 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

              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 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 configuration  parameter.  The
                     parameter  value  can  refer to other parameters as $name
                     etc., just like in  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 Example:

                         submission inet .... smtpd
                             -o smtpd_xxx_yyy=$submission_xxx_yyy

                         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

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

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

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

       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

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