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 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 · 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 pass The service listens on a UNIX-domain socket, receives one
99 open connection (file descriptor passing) per connection
100 request, and is accessible to local clients only.
101 The service name is a pathname relative to the Postfix
103 queue directory (pathname controlled with the
104 queue_directory configuration parameter in main.cf).
105 This feature is available as of Postfix version 2.5.
107 Private (default: y)
109 Whether or not access is restricted to the mail system. Inter‐
110 net (type inet) services can't be private.
111 Unprivileged (default: y)
113 Whether the service runs with root privileges or as the owner of
114 the Postfix system (the owner name is controlled by the
115 mail_owner configuration variable in the main.cf file).
116 The local(8), pipe(8), spawn(8), and virtual(8) daemons require
118 privileges.
119 Chroot (default: y)
121 Whether or not the service runs chrooted to the mail queue
122 directory (pathname is controlled by the queue_directory config‐
123 uration variable in the main.cf file).
124 Chroot should not be used with the local(8), pipe(8), spawn(8),
126 and virtual(8) daemons. Although the proxymap(8) server can run
127 chrooted, doing so defeats most of the purpose of having that
128 service in the first place.
129 The files in the examples/chroot-setup subdirectory of the Post‐
131 fix source archive show set up a Postfix chroot environment on a
132 variety of systems. See also BASIC_CONFIGURATION_README for
133 issues related to running daemons chrooted.
134 Wake up time (default: 0)
136 Automatically wake up the named service after the specified num‐
137 ber of seconds. The wake up is implemented by connecting to the
138 service and sending a wake up request. A ? at the end of the
139 wake-up time field requests that no wake up events be sent
140 before the first time a service is used. Specify 0 for no auto‐
141 matic wake up.
142 The pickup(8), qmgr(8) and flush(8) daemons require a wake up
144 timer.
145 Process limit (default: $default_process_limit)
147 The maximum number of processes that may execute this service
148 simultaneously. Specify 0 for no process count limit.
149 NOTE: Some Postfix services must be configured as a single-
151 process service (for example, qmgr(8)) and some services must be
152 configured with no process limit (for example, cleanup(8)).
153 These limits must not be changed.
154 Command name + arguments
156 The command to be executed. Characters that are special to the
157 shell such as ">" or "|" have no special meaning here, and
158 quotes cannot be used to protect arguments containing white‐
159 space.
160 The command name is relative to the Postfix daemon directory
162 (pathname is controlled by the daemon_directory configuration
163 variable).
164 The command argument syntax for specific commands is specified
166 in the respective daemon manual page.
167 The following command-line options have the same effect for all
169 daemon programs:
170 -D Run the daemon under control by the command specified
172 with the debugger_command variable in the main.cf config‐
173 uration file. See DEBUG_README for hints and tips.
174 -o name=value
176 Override the named main.cf configuration parameter. The
177 parameter value can refer to other parameters as $name
178 etc., just like in main.cf. See postconf(5) for syntax.
179 NOTE 1: do not specify whitespace around the "=". In
181 parameter values, either avoid whitespace altogether, use
182 commas instead of spaces, or consider overrides like "-o
183 name=$override_parameter" with $override_parameter set in
184 main.cf.
185 NOTE 2: Over-zealous use of parameter overrides makes the
187 Postfix configuration hard to understand and maintain.
188 At a certain point, it might be easier to configure mul‐
189 tiple instances of Postfix, instead of configuring multi‐
190 ple personalities via master.cf.
191 -v Increase the verbose logging level. Specify multiple -v
193 options to make a Postfix daemon process increasingly
194 verbose.
195
197 master(8), process manager
198 postconf(5), configuration parameters
199
201 Use "postconf readme_directory" or "postconf html_directory" to locate
202 this information.
203 BASIC_CONFIGURATION_README, basic configuration
204 DEBUG_README, Postfix debugging
205
207 The Secure Mailer license must be distributed with this software.
208
210 Initial version by
211 Magnus Baeck
212 Lund Institute of Technology
213 Sweden
214 Wietse Venema
216 IBM T.J. Watson Research
217 P.O. Box 704
218 Yorktown Heights, NY 10598, USA
219 MASTER(5)