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

6       master - Postfix master process configuration file format
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DESCRIPTION

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.
12
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.
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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.
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25       After  changing  master.cf  you must execute "postfix reload" to reload
26       the configuration.
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SYNTAX

29       The general format of the master.cf file is as follows:
30
31       ·      Each logical line defines a single Postfix service.   Each  ser‐
32              vice  is  identified  by  its  name and type as described below.
33              When multiple lines specify the same service name and type, only
34              the  last  one is remembered.  Otherwise, the order of master.cf
35              service definitions does not matter.
36
37       ·      Empty lines and whitespace-only lines are ignored, as are  lines
38              whose first non-whitespace character is a `#'.
39
40       ·      A  logical  line  starts  with  non-whitespace text. A line that
41              starts with whitespace continues a logical line.
42
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.
46
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.
50
51       Service name
52              The service name syntax depends on the service type as described
53              next.
54
55       Service type
56              Specify one of the following service types:
57
58              inet   The  service listens on a TCP/IP socket and is accessible
59                     via the network.
60
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 (host
65                     or service name) or in numeric form (IP address  or  port
66                     number).   Host  information may be enclosed inside "[]",
67                     but this form is not necessary.
68
69                     Examples: a  service  named  127.0.0.1:smtp  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.
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75
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.
80
81              unix   The service listens on a UNIX-domain socket and is acces‐
82                     sible for local clients only.
83
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).
87
88                     On Solaris systems the  unix  type  is  implemented  with
89                     streams sockets.
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91              fifo   The  service listens on a FIFO (named pipe) and is acces‐
92                     sible for local clients only.
93
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).
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98              pass   The service listens on a UNIX-domain socket, receives one
99                     open  connection (file descriptor passing) per connection
100                     request, and is accessible to local clients only.
101
102                     The service name is a pathname relative  to  the  Postfix
103                     queue    directory    (pathname   controlled   with   the
104                     queue_directory configuration parameter in main.cf).
105
106                     This feature is available as of Postfix version 2.5.
107
108       Private (default: y)
109              Whether or not access is restricted to the mail system.   Inter‐
110              net (type inet) services can't be private.
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112       Unprivileged (default: y)
113              Whether the service runs with root privileges or as the owner of
114              the  Postfix  system  (the  owner  name  is  controlled  by  the
115              mail_owner configuration variable in the main.cf file).
116
117              The  local(8), pipe(8), spawn(8), and virtual(8) daemons require
118              privileges.
119
120       Chroot (default: y)
121              Whether or not the service  runs  chrooted  to  the  mail  queue
122              directory (pathname is controlled by the queue_directory config‐
123              uration variable in the main.cf file).
124
125              Chroot should not be used with the local(8), pipe(8),  spawn(8),
126              and virtual(8) daemons.  Although the proxymap(8) server can run
127              chrooted, doing so defeats most of the purpose  of  having  that
128              service in the first place.
129
130              The files in the examples/chroot-setup subdirectory of the Post‐
131              fix source archive show set up a Postfix chroot environment on a
132              variety  of  systems.  See  also  BASIC_CONFIGURATION_README for
133              issues related to running daemons chrooted.
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135       Wake up time (default: 0)
136              Automatically wake up the named service after the specified num‐
137              ber  of seconds. The wake up is implemented by connecting to the
138              service and sending a wake up request.  A ? at the  end  of  the
139              wake-up  time  field  requests  that  no  wake up events be sent
140              before the first time a service is used.  Specify 0 for no auto‐
141              matic wake up.
142
143              The  pickup(8),  qmgr(8)  and flush(8) daemons require a wake up
144              timer.
145
146       Process limit (default: $default_process_limit)
147              The maximum number of processes that may  execute  this  service
148              simultaneously. Specify 0 for no process count limit.
149
150              NOTE:  Some  Postfix  services  must  be configured as a single-
151              process service (for example, qmgr(8)) and some services must be
152              configured  with  no  process  limit  (for example, cleanup(8)).
153              These limits must not be changed.
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155       Command name + arguments
156              The command to be executed.  Characters that are special to  the
157              shell  such  as  ">"  or  "|"  have no special meaning here, and
158              quotes cannot be used to  protect  arguments  containing  white‐
159              space.
160
161              The  command  name  is  relative to the Postfix daemon directory
162              (pathname is controlled by  the  daemon_directory  configuration
163              variable).
164
165              The  command  argument syntax for specific commands is specified
166              in the respective daemon manual page.
167
168              The following command-line options have the same effect for  all
169              daemon programs:
170
171              -D     Run  the  daemon  under  control by the command specified
172                     with the debugger_command variable in the main.cf config‐
173                     uration file.  See DEBUG_README for hints and tips.
174
175              -o name=value
176                     Override  the  named main.cf configuration parameter. The
177                     parameter value can refer to other  parameters  as  $name
178                     etc., just like in main.cf.  See postconf(5) for syntax.
179
180                     NOTE  1:  do  not  specify  whitespace around the "=". In
181                     parameter values, either avoid whitespace altogether, use
182                     commas  instead of spaces, or consider overrides like "-o
183                     name=$override_parameter" with $override_parameter set in
184                     main.cf.
185
186                     NOTE 2: Over-zealous use of parameter overrides makes the
187                     Postfix configuration hard to  understand  and  maintain.
188                     At  a certain point, it might be easier to configure mul‐
189                     tiple instances of Postfix, instead of configuring multi‐
190                     ple personalities via master.cf.
191
192              -v     Increase  the  verbose logging level. Specify multiple -v
193                     options to make a  Postfix  daemon  process  increasingly
194                     verbose.
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SEE ALSO

197       master(8), process manager
198       postconf(5), configuration parameters
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README FILES

201       Use  "postconf readme_directory" or "postconf html_directory" to locate
202       this information.
203       BASIC_CONFIGURATION_README, basic configuration
204       DEBUG_README, Postfix debugging
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LICENSE

207       The Secure Mailer license must be distributed with this software.
208

AUTHOR(S)

210       Initial version by
211       Magnus Baeck
212       Lund Institute of Technology
213       Sweden
214
215       Wietse Venema
216       IBM T.J. Watson Research
217       P.O. Box 704
218       Yorktown Heights, NY 10598, USA
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