1MASTER(5) File Formats Manual MASTER(5)
2
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 or not access is restricted to the mail system. Inter‐
123 net (type inet) services can't be private.
124 Unprivileged (default: y)
126 Whether the service runs with root privileges or as the owner of
127 the Postfix system (the owner name is controlled by the
128 mail_owner configuration variable in the main.cf file).
129 The local(8), pipe(8), spawn(8), and virtual(8) daemons require
131 privileges.
132 Chroot (default: Postfix >= 3.0: n, Postfix <3.0: y)
134 Whether or not the service runs chrooted to the mail queue di‐
135 rectory (pathname is controlled by the queue_directory configu‐
136 ration variable in the main.cf file).
137 Chroot should not be used with the local(8), pipe(8), spawn(8),
139 and virtual(8) daemons. Although the proxymap(8) server can run
140 chrooted, doing so defeats most of the purpose of having that
141 service in the first place.
142 The files in the examples/chroot-setup subdirectory of the Post‐
144 fix source show how to set up a Postfix chroot environment on a
145 variety of systems. See also BASIC_CONFIGURATION_README for is‐
146 sues related to running daemons chrooted.
147 Wake up time (default: 0)
149 Automatically wake up the named service after the specified num‐
150 ber of seconds. The wake up is implemented by connecting to the
151 service and sending a wake up request. A ? at the end of the
152 wake-up time field requests that no wake up events be sent be‐
153 fore the first time a service is used. Specify 0 for no auto‐
154 matic wake up.
155 The pickup(8), qmgr(8) and flush(8) daemons require a wake up
157 timer.
158 Process limit (default: $default_process_limit)
160 The maximum number of processes that may execute this service
161 simultaneously. Specify 0 for no process count limit.
162 NOTE: Some Postfix services must be configured as a sin‐
164 gle-process service (for example, qmgr(8)) and some services
165 must be configured with no process limit (for example,
166 cleanup(8)). These limits must not be changed.
167 Command name + arguments
169 The command to be executed. Characters that are special to the
170 shell such as ">" or "|" have no special meaning here, and
171 quotes cannot be used to protect arguments containing white‐
172 space. To protect whitespace, use "{" and "}" as described be‐
173 low.
174 The command name is relative to the Postfix daemon directory
176 (pathname is controlled by the daemon_directory configuration
177 variable).
178 The command argument syntax for specific commands is specified
180 in the respective daemon manual page.
181 The following command-line options have the same effect for all
183 daemon programs:
184 -D Run the daemon under control by the command specified
186 with the debugger_command variable in the main.cf config‐
187 uration file. See DEBUG_README for hints and tips.
188 -o { name = value } (long form, Postfix >= 3.0)
190 -o name=value (short form)
192 Override the named main.cf configuration parameter. The
193 parameter value can refer to other parameters as $name
194 etc., just like in main.cf. See postconf(5) for syntax.
195 NOTE 1: With the "long form" shown above, whitespace af‐
197 ter "{", around "=", and before "}" is ignored, and
198 whitespace within the parameter value is preserved.
199 NOTE 2: with the "short form" shown above, do not specify
201 whitespace around the "=" or in parameter values. To
202 specify a parameter value that contains whitespace, use
203 the long form described above, or use commas instead of
204 spaces, or specify the value in main.cf. Example:
205 /etc/postfix/master.cf:
207 submission inet .... smtpd
208 -o smtpd_xxx_yyy=$submission_xxx_yyy
209 /etc/postfix/main.cf
211 submission_xxx_yyy = text with whitespace...
212 NOTE 3: Over-zealous use of parameter overrides makes the
214 Postfix configuration hard to understand and maintain.
215 At a certain point, it might be easier to configure mul‐
216 tiple instances of Postfix, instead of configuring multi‐
217 ple personalities via master.cf.
218 -v Increase the verbose logging level. Specify multiple -v
220 options to make a Postfix daemon process increasingly
221 verbose.
222 Other command-line arguments
224 Specify "{" and "}" around command arguments that contain
225 whitespace (Postfix 3.0 and later). Whitespace after "{"
226 and before "}" is ignored.
227
229 master(8), process manager
230 postconf(5), configuration parameters
231
233 Use "postconf readme_directory" or "postconf html_directory" to locate
234 this information.
235 BASIC_CONFIGURATION_README, basic configuration
236 DEBUG_README, Postfix debugging
237
239 The Secure Mailer license must be distributed with this software.
240
242 Initial version by
243 Magnus Baeck
244 Lund Institute of Technology
245 Sweden
246 Wietse Venema
248 IBM T.J. Watson Research
249 P.O. Box 704
250 Yorktown Heights, NY 10598, USA
251 Wietse Venema
253 Google, Inc.
254 111 8th Avenue
255 New York, NY 10011, USA
256 MASTER(5)