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 (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 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 systems the pass type is implemented with
108 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: 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 archive show 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 single-
155 process service (for example, qmgr(8)) and some services must be
156 configured with no process limit (for example, cleanup(8)).
157 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.
164 The command name is relative to the Postfix daemon directory
166 (pathname is controlled by the daemon_directory configuration
167 variable).
168 The command argument syntax for specific commands is specified
170 in the respective daemon manual page.
171 The following command-line options have the same effect for all
173 daemon programs:
174 -D Run the daemon under control by the command specified
176 with the debugger_command variable in the main.cf config‐
177 uration file. See DEBUG_README for hints and tips.
178 -o name=value
180 Override the named main.cf configuration parameter. The
181 parameter value can refer to other parameters as $name
182 etc., just like in main.cf. See postconf(5) for syntax.
183 NOTE 1: do not specify whitespace around the "=" or in
185 parameter values. To specify a parameter value that con‐
186 tains whitespace, use commas instead of spaces, or spec‐
187 ify the value in main.cf. Example:
188 /etc/postfix/master.cf:
190 submission inet .... smtpd
191 -o smtpd_mumble=$submission_mumble
192 /etc/postfix/main.cf
194 submission_mumble = text with whitespace...
195 NOTE 2: Over-zealous use of parameter overrides makes the
197 Postfix configuration hard to understand and maintain.
198 At a certain point, it might be easier to configure mul‐
199 tiple instances of Postfix, instead of configuring multi‐
200 ple personalities via master.cf.
201 -v Increase the verbose logging level. Specify multiple -v
203 options to make a Postfix daemon process increasingly
204 verbose.
205
207 master(8), process manager
208 postconf(5), configuration parameters
209
211 Use "postconf readme_directory" or "postconf html_directory" to locate
212 this information.
213 BASIC_CONFIGURATION_README, basic configuration
214 DEBUG_README, Postfix debugging
215
217 The Secure Mailer license must be distributed with this software.
218
220 Initial version by
221 Magnus Baeck
222 Lund Institute of Technology
223 Sweden
224 Wietse Venema
226 IBM T.J. Watson Research
227 P.O. Box 704
228 Yorktown Heights, NY 10598, USA
229 MASTER(5)