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 voluntarily after serving max_use
18 clients, or 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 · Empty lines and whitespace-only lines are ignored, as are lines
32 whose first non-whitespace character is a `#'.
33 · A logical line starts with non-whitespace text. A line that
35 starts with whitespace continues a logical line.
36 · 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.
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 (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.
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 8 and earlier systems the unix type is imple‐
89 mented with 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 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.
102 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).
106 On Solaris 8 and earlier systems the pass type is imple‐
108 mented with streams sockets.
109 This feature is available as of Postfix version 2.5.
111 Private (default: y)
113 Whether or not access is restricted to the mail system. Inter‐
114 net (type inet) services can't be private.
115 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).
120 The local(8), pipe(8), spawn(8), and virtual(8) daemons require
122 privileges.
123 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).
128 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.
133 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.
138 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.
146 The pickup(8), qmgr(8) and flush(8) daemons require a wake up
148 timer.
149 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.
153 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.
158 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.
165 The command name is relative to the Postfix daemon directory
167 (pathname is controlled by the daemon_directory configuration
168 variable).
169 The command argument syntax for specific commands is specified
171 in the respective daemon manual page.
172 The following command-line options have the same effect for all
174 daemon programs:
175 -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.
179 -o { name = value } (long form, Postfix >= 3.0)
181 -o name=value (short form)
183 Override the named main.cf configuration parameter. The
184 parameter value can refer to other parameters as $name
185 etc., just like in main.cf. See postconf(5) for syntax.
186 NOTE 1: With the "long form" shown above, whitespace
188 after "{", around "=", and before "}" is ignored, and
189 whitespace within the parameter value is preserved.
190 NOTE 2: with the "short form" shown above, do not specify
192 whitespace around the "=" or in parameter values. To
193 specify a parameter value that contains whitespace, use
194 the long form described above, or use commas instead of
195 spaces, or specify the value in main.cf. Example:
196 /etc/postfix/master.cf:
198 submission inet .... smtpd
199 -o smtpd_xxx_yyy=$submission_xxx_yyy
200 /etc/postfix/main.cf
202 submission_xxx_yyy = text with whitespace...
203 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.
209 -v Increase the verbose logging level. Specify multiple -v
211 options to make a Postfix daemon process increasingly
212 verbose.
213 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.
218
220 master(8), process manager
221 postconf(5), configuration parameters
222
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
228
230 The Secure Mailer license must be distributed with this software.
231
233 Initial version by
234 Magnus Baeck
235 Lund Institute of Technology
236 Sweden
237 Wietse Venema
239 IBM T.J. Watson Research
240 P.O. Box 704
241 Yorktown Heights, NY 10598, USA
242 Wietse Venema
244 Google, Inc.
245 111 8th Avenue
246 New York, NY 10011, USA
247 MASTER(5)