1MASTER(5) File Formats Manual MASTER(5)
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6 master - Postfix master process configuration file format
7
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 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 after serving max_use clients, or
18 after inactivity for max_idle or more units of time.
19 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.
24 After changing master.cf you must execute "postfix reload" to reload
26 the configuration.
27
29 The general format of the master.cf file is as follows:
30 · 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 · Empty lines and whitespace-only lines are ignored, as are lines
38 whose first non-whitespace character is a `#'.
39 · A logical line starts with non-whitespace text. A line that
41 starts with whitespace continues a logical line.
42 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 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 Service name
52 The service name syntax depends on the service type as described
53 next.
54 Service type
56 Specify one of the following service types:
57 inet The service listens on a TCP/IP socket and is accessible
59 via the network.
60 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 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.
74 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 unix The service listens on a UNIX-domain socket and is acces‐
82 sible for local clients only.
83 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 On Solaris systems the unix type is implemented with
89 streams sockets.
90 fifo The service listens on a FIFO (named pipe) and is acces‐
92 sible for local clients only.
93 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).
97 Private (default: y)
99 Whether or not access is restricted to the mail system. Inter‐
100 net (type inet) services can't be private.
101 Unprivileged (default: y)
103 Whether the service runs with root privileges or as the owner of
104 the Postfix system (the owner name is controlled by the
105 mail_owner configuration variable in the main.cf file).
106 The local(8), pipe(8), spawn(8), and virtual(8) daemons require
108 privileges.
109 Chroot (default: y)
111 Whether or not the service runs chrooted to the mail queue
112 directory (pathname is controlled by the queue_directory config‐
113 uration variable in the main.cf file).
114 Chroot should not be used with the local(8), pipe(8), spawn(8),
116 and virtual(8) daemons. Although the proxymap(8) server can run
117 chrooted, doing so defeats most of the purpose of having that
118 service in the first place.
119 The files in the examples/chroot-setup subdirectory of the Post‐
121 fix source archive show set up a Postfix chroot environment on a
122 variety of systems. See also BASIC_CONFIGURATION_README for
123 issues related to running daemons chrooted.
124 Wake up time (default: 0)
126 Automatically wake up the named service after the specified num‐
127 ber of seconds. The wake up is implemented by connecting to the
128 service and sending a wake up request. A ? at the end of the
129 wake-up time field requests that no wake up events be sent
130 before the first time a service is used. Specify 0 for no auto‐
131 matic wake up.
132 The pickup(8), qmgr(8) and flush(8) daemons require a wake up
134 timer.
135 Process limit (default: $default_process_limit)
137 The maximum number of processes that may execute this service
138 simultaneously. Specify 0 for no process count limit.
139 NOTE: Some Postfix services must be configured as a single-
141 process service (for example, qmgr(8)) and some services must be
142 configured with no process limit (for example, cleanup(8)).
143 These limits must not be changed.
144 Command name + arguments
146 The command to be executed. Characters that are special to the
147 shell such as ">" or "|" have no special meaning here, and
148 quotes cannot be used to protect arguments containing white‐
149 space.
150 The command name is relative to the Postfix daemon directory
152 (pathname is controlled by the daemon_directory configuration
153 variable).
154 The command argument syntax for specific commands is specified
156 in the respective daemon manual page.
157 The following command-line options have the same effect for all
159 daemon programs:
160 -D Run the daemon under control by the command specified
162 with the debugger_command variable in the main.cf config‐
163 uration file. See DEBUG_README for hints and tips.
164 -o name=value
166 Override the named main.cf configuration parameter. The
167 parameter value can refer to other parameters as $name
168 etc., just like in main.cf. See postconf(5) for syntax.
169 NOTE 1: do not specify whitespace around the "=". In
171 parameter values, either avoid whitespace altogether, use
172 commas instead of spaces, or consider overrides like "-o
173 name=$override_parameter" with $override_parameter set in
174 main.cf.
175 NOTE 2: Over-zealous use of parameter overrides makes the
177 Postfix configuration hard to understand and maintain.
178 At a certain point, it might be easier to configure mul‐
179 tiple instances of Postfix, instead of configuring multi‐
180 ple personalities via master.cf.
181 -v Increase the verbose logging level. Specify multiple -v
183 options to make a Postfix daemon process increasingly
184 verbose.
185
187 master(8), process manager
188 postconf(5), configuration parameters
189
191 Use "postconf readme_directory" or "postconf html_directory" to locate
192 this information.
193 BASIC_CONFIGURATION_README, basic configuration
194 DEBUG_README, Postfix debugging
195
197 The Secure Mailer license must be distributed with this software.
198
200 Initial version by
201 Magnus Baeck
202 Lund Institute of Technology
203 Sweden
204 Wietse Venema
206 IBM T.J. Watson Research
207 P.O. Box 704
208 Yorktown Heights, NY 10598, USA
209 MASTER(5)