1MASTER(5)                     File Formats Manual                    MASTER(5)


6       master - Postfix master process configuration file format


9       The  Postfix  mail  system  is  implemented by small number of (mostly)
10       client commands that are invoked by users, and by a  larger  number  of
11       services that run in the background.
13       Postfix  services are implemented by daemon processes. These run in the
14       background under control of the master(8) process.  The master.cf  con‐
15       figuration file defines how a client program connects to a service, and
16       what daemon program runs when a service is requested.  Most daemon pro‐
17       cesses  are short-lived and terminate voluntarily after serving max_use
18       clients, or after inactivity for max_idle or more units of time.
20       All daemons specified here must speak a Postfix-internal  protocol.  In
21       order  to  execute  non-Postfix  software  use the local(8), pipe(8) or
22       spawn(8) services, or run the  server  under  control  by  inetd(8)  or
23       equivalent.
25       After  changing  master.cf  you must execute "postfix reload" to reload
26       the configuration.


29       The general format of the master.cf file is as follows:
31       ·      Empty lines and whitespace-only lines are ignored, as are  lines
32              whose first non-whitespace character is a `#'.
34       ·      A  logical  line  starts  with  non-whitespace text. A line that
35              starts with whitespace continues a logical line.
37       ·      Each logical line defines a single Postfix service.   Each  ser‐
38              vice  is  identified  by  its  name and type as described below.
39              When multiple lines specify the same service name and type, only
40              the  last  one is remembered.  Otherwise, the order of master.cf
41              service definitions does not matter.
43       Each logical line consists of eight  fields  separated  by  whitespace.
44       These  are described below in the order as they appear in the master.cf
45       file.
47       Where applicable a field of "-"  requests  that  the  built-in  default
48       value  be  used.  For boolean fields specify "y" or "n" to override the
49       default value.
51       Service name
52              The service name syntax depends on the service type as described
53              next.
55       Service type
56              Specify one of the following service types:
58              inet   The  service listens on a TCP/IP socket and is accessible
59                     via the network.
61                     The service name is specified as host:port, denoting  the
62                     host   and  port  on  which  new  connections  should  be
63                     accepted. The host  part  (and  colon)  may  be  omitted.
64                     Either  host  or  port may be given in symbolic form (see
65                     hosts(5) or services(5)) or in numeric form  (IP  address
66                     or port number).  Host information may be enclosed inside
67                     "[]"; this form is necessary only with IPv6 addresses.
69                     Examples: a  service  named  or  ::1:smtp
70                     receives mail via the loopback interface only; and a ser‐
71                     vice named 10025 accepts connections on  TCP  port  10025
72                     via  all  interfaces  configured with the inet_interfaces
73                     parameter.
76                     Note:  with  Postfix  version  2.2  and   later   specify
77                     "inet_interfaces  = loopback-only" in main.cf, instead of
78                     hard-coding loopback IP address information in  master.cf
79                     or in main.cf.
81              unix   The service listens on a UNIX-domain socket and is acces‐
82                     sible for local clients only.
84                     The service name is a pathname relative  to  the  Postfix
85                     queue    directory    (pathname   controlled   with   the
86                     queue_directory configuration parameter in main.cf).
88                     On Solaris 8 and earlier systems the unix type is  imple‐
89                     mented with streams sockets.
91              fifo   The  service listens on a FIFO (named pipe) and is acces‐
92                     sible for local clients only.
94                     The service name is a pathname relative  to  the  Postfix
95                     queue    directory    (pathname   controlled   with   the
96                     queue_directory configuration parameter in main.cf).
98              pass   The service listens  on  a  UNIX-domain  socket,  and  is
99                     accessible  to  local  clients only. It receives one open
100                     connection  (file  descriptor  passing)  per   connection
101                     request.
103                     The  service  name  is a pathname relative to the Postfix
104                     queue   directory   (pathname   controlled    with    the
105                     queue_directory configuration parameter in main.cf).
107                     On  Solaris 8 and earlier systems the pass type is imple‐
108                     mented with streams sockets.
110                     This feature is available as of Postfix version 2.5.
112       Private (default: y)
113              Whether or not access is restricted to the mail system.   Inter‐
114              net (type inet) services can't be private.
116       Unprivileged (default: y)
117              Whether the service runs with root privileges or as the owner of
118              the  Postfix  system  (the  owner  name  is  controlled  by  the
119              mail_owner configuration variable in the main.cf file).
121              The  local(8), pipe(8), spawn(8), and virtual(8) daemons require
122              privileges.
124       Chroot (default: Postfix >= 3.0: n, Postfix <3.0: y)
125              Whether or not the service  runs  chrooted  to  the  mail  queue
126              directory (pathname is controlled by the queue_directory config‐
127              uration variable in the main.cf file).
129              Chroot should not be used with the local(8), pipe(8),  spawn(8),
130              and virtual(8) daemons.  Although the proxymap(8) server can run
131              chrooted, doing so defeats most of the purpose  of  having  that
132              service in the first place.
134              The files in the examples/chroot-setup subdirectory of the Post‐
135              fix source show how to set up a Postfix chroot environment on  a
136              variety  of  systems.  See  also  BASIC_CONFIGURATION_README for
137              issues related to running daemons chrooted.
139       Wake up time (default: 0)
140              Automatically wake up the named service after the specified num‐
141              ber  of seconds. The wake up is implemented by connecting to the
142              service and sending a wake up request.  A ? at the  end  of  the
143              wake-up  time  field  requests  that  no  wake up events be sent
144              before the first time a service is used.  Specify 0 for no auto‐
145              matic wake up.
147              The  pickup(8),  qmgr(8)  and flush(8) daemons require a wake up
148              timer.
150       Process limit (default: $default_process_limit)
151              The maximum number of processes that may  execute  this  service
152              simultaneously. Specify 0 for no process count limit.
154              NOTE:  Some  Postfix  services  must  be  configured  as  a sin‐
155              gle-process service (for example,  qmgr(8))  and  some  services
156              must   be   configured  with  no  process  limit  (for  example,
157              cleanup(8)).  These limits must not be changed.
159       Command name + arguments
160              The command to be executed.  Characters that are special to  the
161              shell  such  as  ">"  or  "|"  have no special meaning here, and
162              quotes cannot be used to  protect  arguments  containing  white‐
163              space.  To  protect  whitespace,  use  "{"  and "}" as described
164              below.
166              The command name is relative to  the  Postfix  daemon  directory
167              (pathname  is  controlled  by the daemon_directory configuration
168              variable).
170              The command argument syntax for specific commands  is  specified
171              in the respective daemon manual page.
173              The  following command-line options have the same effect for all
174              daemon programs:
176              -D     Run the daemon under control  by  the  command  specified
177                     with the debugger_command variable in the main.cf config‐
178                     uration file.  See DEBUG_README for hints and tips.
180              -o { name = value } (long form, Postfix >= 3.0)
182              -o name=value (short form)
183                     Override the named main.cf configuration  parameter.  The
184                     parameter  value  can  refer to other parameters as $name
185                     etc., just like in main.cf.  See postconf(5) for syntax.
187                     NOTE 1: With the  "long  form"  shown  above,  whitespace
188                     after  "{",  around  "=",  and before "}" is ignored, and
189                     whitespace within the parameter value is preserved.
191                     NOTE 2: with the "short form" shown above, do not specify
192                     whitespace  around  the  "="  or  in parameter values. To
193                     specify a parameter value that contains  whitespace,  use
194                     the  long  form described above, or use commas instead of
195                     spaces, or specify the value in main.cf. Example:
197                     /etc/postfix/master.cf:
198                         submission inet .... smtpd
199                             -o smtpd_xxx_yyy=$submission_xxx_yyy
201                     /etc/postfix/main.cf
202                         submission_xxx_yyy = text with whitespace...
204                     NOTE 3: Over-zealous use of parameter overrides makes the
205                     Postfix  configuration  hard  to understand and maintain.
206                     At a certain point, it might be easier to configure  mul‐
207                     tiple instances of Postfix, instead of configuring multi‐
208                     ple personalities via master.cf.
210              -v     Increase the verbose logging level. Specify  multiple  -v
211                     options  to  make  a  Postfix daemon process increasingly
212                     verbose.
214              Other command-line arguments
215                     Specify "{" and "}" around command arguments that contain
216                     whitespace  (Postfix 3.0 and later). Whitespace after "{"
217                     and before "}" is ignored.


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


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


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


233       Initial version by
234       Magnus Baeck
235       Lund Institute of Technology
236       Sweden
238       Wietse Venema
239       IBM T.J. Watson Research
240       P.O. Box 704
241       Yorktown Heights, NY 10598, USA
243       Wietse Venema
244       Google, Inc.
245       111 8th Avenue
246       New York, NY 10011, USA
250                                                                     MASTER(5)