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, started on-demand by the master(8) process. The master.cf
15 configuration file defines how a client program connects to a service,
16 and what daemon program runs when a service is requested. Most daemon
17 processes are short-lived and terminate voluntarily after serving
18 max_use clients, or after inactivity for max_idle or more units of
19 time.
20 All daemons specified here must speak a Postfix-internal protocol. In
22 order to execute non-Postfix software use the local(8), pipe(8) or
23 spawn(8) services, or execute the software with inetd(8) or 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 ac‐
63 cepted. The host part (and colon) may be omitted. Either
64 host or port may be given in symbolic form (see hosts(5)
65 or services(5)) or in numeric form (IP address or port
66 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 re‐
70 ceives 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 stream socket and is
82 accessible for local clients only.
83 The service name is a pathname relative to the Postfix
85 queue directory (pathname controlled with the queue_di‐
86 rectory configuration parameter in main.cf).
87 On Solaris 8 and earlier systems the unix type is imple‐
89 mented with streams sockets.
90 unix-dgram
92 The service listens on a UNIX-domain datagram socket and
93 is accessible for local clients only.
94 The service name is a pathname relative to the Postfix
96 queue directory (pathname controlled with the queue_di‐
97 rectory configuration parameter in main.cf).
98 fifo (obsolete)
100 The service listens on a FIFO (named pipe) and is acces‐
101 sible for local clients only.
102 The service name is a pathname relative to the Postfix
104 queue directory (pathname controlled with the queue_di‐
105 rectory configuration parameter in main.cf).
106 pass The service listens on a UNIX-domain stream socket, and
108 is accessible to local clients only. It receives one open
109 connection (file descriptor passing) per connection re‐
110 quest.
111 The service name is a pathname relative to the Postfix
113 queue directory (pathname controlled with the queue_di‐
114 rectory configuration parameter in main.cf).
115 On Solaris 8 and earlier systems the pass type is imple‐
117 mented with streams sockets.
118 This feature is available as of Postfix version 2.5.
120 Private (default: y)
122 Whether a service is internal to Postfix (pathname starts with
123 private/), or exposed through Postfix command-line tools (path‐
124 name starts with public/). Internet (type inet) services can't
125 be private.
126 Unprivileged (default: y)
128 Whether the service runs with root privileges or as the owner of
129 the Postfix system (the owner name is controlled by the
130 mail_owner configuration variable in the main.cf file).
131 The local(8), pipe(8), spawn(8), and virtual(8) daemons require
133 privileges.
134 Chroot (default: Postfix >= 3.0: n, Postfix < 3.0: y)
136 Whether or not the service runs chrooted to the mail queue di‐
137 rectory (pathname is controlled by the queue_directory configu‐
138 ration variable in the main.cf file).
139 Chroot should not be used with the local(8), pipe(8), spawn(8),
141 and virtual(8) daemons. Although the proxymap(8) server can run
142 chrooted, doing so defeats most of the purpose of having that
143 service in the first place.
144 The files in the examples/chroot-setup subdirectory of the Post‐
146 fix source show how to set up a Postfix chroot environment on a
147 variety of systems. See also BASIC_CONFIGURATION_README for is‐
148 sues related to running daemons chrooted.
149 Wake up time (default: 0)
151 Automatically wake up the named service after the specified num‐
152 ber of seconds. The wake up is implemented by connecting to the
153 service and sending a wake up request. A ? at the end of the
154 wake-up time field requests that no wake up events be sent be‐
155 fore the first time a service is used. Specify 0 for no auto‐
156 matic wake up.
157 The pickup(8), qmgr(8) and flush(8) daemons require a wake up
159 timer.
160 Process limit (default: $default_process_limit)
162 The maximum number of processes that may execute this service
163 simultaneously. Specify 0 for no process count limit.
164 NOTE: Some Postfix services must be configured as a sin‐
166 gle-process service (for example, qmgr(8)) and some services
167 must be configured with no process limit (for example,
168 cleanup(8)). These limits must not be changed.
169 Command name + arguments
171 The command to be executed. Characters that are special to the
172 shell such as ">" or "|" have no special meaning here, and
173 quotes cannot be used to protect arguments containing white‐
174 space. To protect whitespace, use "{" and "}" as described be‐
175 low.
176 The command name is relative to the Postfix daemon directory
178 (pathname is controlled by the daemon_directory configuration
179 variable).
180 The command argument syntax for specific commands is specified
182 in the respective daemon manual page.
183 The following command-line options have the same effect for all
185 daemon programs:
186 -D Run the daemon under control by the command specified
188 with the debugger_command variable in the main.cf config‐
189 uration file. See DEBUG_README for hints and tips.
190 -o { name = value } (long form, Postfix >= 3.0)
192 -o name=value (short form)
194 Override the named main.cf configuration parameter. The
195 parameter value can refer to other parameters as $name
196 etc., just like in main.cf. See postconf(5) for syntax.
197 NOTE 1: With the "long form" shown above, whitespace af‐
199 ter "{", around "=", and before "}" is ignored, and
200 whitespace within the parameter value is preserved.
201 NOTE 2: with the "short form" shown above, do not specify
203 whitespace around the "=" or in parameter values. To
204 specify a parameter value that contains whitespace, use
205 the long form described above, or use commas instead of
206 spaces, or specify the value in main.cf. Example:
207 /etc/postfix/master.cf:
209 submission inet .... smtpd
210 -o smtpd_xxx_yyy=$submission_xxx_yyy
211 /etc/postfix/main.cf
213 submission_xxx_yyy = text with whitespace...
214 NOTE 3: Over-zealous use of parameter overrides makes the
216 Postfix configuration hard to understand and maintain.
217 At a certain point, it might be easier to configure mul‐
218 tiple instances of Postfix, instead of configuring multi‐
219 ple personalities via master.cf.
220 -v Increase the verbose logging level. Specify multiple -v
222 options to make a Postfix daemon process increasingly
223 verbose.
224 Other command-line arguments
226 Specify "{" and "}" around command arguments that contain
227 whitespace (Postfix 3.0 and later). Whitespace after "{"
228 and before "}" is ignored.
229
231 master(8), process manager
232 postconf(5), configuration parameters
233
235 Use "postconf readme_directory" or "postconf html_directory" to locate
236 this information.
237 BASIC_CONFIGURATION_README, basic configuration
238 DEBUG_README, Postfix debugging
239
241 The Secure Mailer license must be distributed with this software.
242
244 Initial version by
245 Magnus Baeck
246 Lund Institute of Technology
247 Sweden
248 Wietse Venema
250 IBM T.J. Watson Research
251 P.O. Box 704
252 Yorktown Heights, NY 10598, USA
253 Wietse Venema
255 Google, Inc.
256 111 8th Avenue
257 New York, NY 10011, USA
258 MASTER(5)