1VIRTUAL(8) System Manager's Manual VIRTUAL(8)
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6 virtual - Postfix virtual domain mail delivery agent
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9 virtual [generic Postfix daemon options]
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12 The virtual(8) delivery agent is designed for virtual mail hosting ser‐
13 vices. Originally based on the Postfix local(8) delivery agent, this
14 agent looks up recipients with map lookups of their full recipient ad‐
15 dress, instead of using hard-coded unix password file lookups of the
16 address local part only.
17 This delivery agent only delivers mail. Other features such as mail
19 forwarding, out-of-office notifications, etc., must be configured via
20 virtual_alias maps or via similar lookup mechanisms.
21
23 The mailbox location is controlled by the virtual_mailbox_base and vir‐
24 tual_mailbox_maps configuration parameters (see below). The vir‐
25 tual_mailbox_maps table is indexed by the recipient address as de‐
26 scribed under TABLE SEARCH ORDER below.
27 The mailbox pathname is constructed as follows:
29 $virtual_mailbox_base/$virtual_mailbox_maps(recipient)
31 where recipient is the full recipient address.
33
35 When the mailbox location does not end in /, the message is delivered
36 in UNIX mailbox format. This format stores multiple messages in one
37 textfile.
38 The virtual(8) delivery agent prepends a "From sender time_stamp" enve‐
40 lope header to each message, prepends a Delivered-To: message header
41 with the envelope recipient address, prepends an X-Original-To: header
42 with the recipient address as given to Postfix, prepends a Return-Path:
43 message header with the envelope sender address, prepends a > character
44 to lines beginning with "From ", and appends an empty line.
45 The mailbox is locked for exclusive access while delivery is in
47 progress. In case of problems, an attempt is made to truncate the mail‐
48 box to its original length.
49
51 When the mailbox location ends in /, the message is delivered in qmail
52 maildir format. This format stores one message per file.
53 The virtual(8) delivery agent prepends a Delivered-To: message header
55 with the final envelope recipient address, prepends an X-Original-To:
56 header with the recipient address as given to Postfix, and prepends a
57 Return-Path: message header with the envelope sender address.
58 By definition, maildir format does not require application-level file
60 locking during mail delivery or retrieval.
61
63 Mailbox ownership is controlled by the virtual_uid_maps and vir‐
64 tual_gid_maps lookup tables, which are indexed with the full recipient
65 address. Each table provides a string with the numerical user and group
66 ID, respectively.
67 The virtual_minimum_uid parameter imposes a lower bound on numerical
69 user ID values that may be specified in any virtual_uid_maps.
70
72 All delivery decisions are made using the full recipient address,
73 folded to lower case. See also the next section for a few exceptions
74 with optional address extensions.
75
77 Normally, a lookup table is specified as a text file that serves as in‐
78 put to the postmap(1) command. The result, an indexed file in dbm or db
79 format, is used for fast searching by the mail system.
80 The search order is as follows. The search stops upon the first suc‐
82 cessful lookup.
83 • When the recipient has an optional address extension the
85 user+extension@domain.tld address is looked up first.
86 With Postfix versions before 2.1, the optional address extension
88 is always ignored.
89 • The user@domain.tld address, without address extension, is
91 looked up next.
92 • Finally, the recipient @domain is looked up.
94 When the table is provided via other means such as NIS, LDAP or SQL,
96 the same lookups are done as for ordinary indexed files.
97 Alternatively, a table can be provided as a regular-expression map
99 where patterns are given as regular expressions. In that case, only the
100 full recipient address is given to the regular-expression map.
101
103 The virtual(8) delivery agent is not security sensitive, provided that
104 the lookup tables with recipient user/group ID information are ade‐
105 quately protected. This program is not designed to run chrooted.
106 The virtual(8) delivery agent disallows regular expression substitution
108 of $1 etc. in regular expression lookup tables, because that would open
109 a security hole.
110 The virtual(8) delivery agent will silently ignore requests to use the
112 proxymap(8) server. Instead it will open the table directly. Before
113 Postfix version 2.2, the virtual delivery agent will terminate with a
114 fatal error.
115
117 RFC 822 (ARPA Internet Text Messages)
118
120 Mail bounces when the recipient has no mailbox or when the recipient is
121 over disk quota. In all other problem cases, mail for an existing re‐
122 cipient is deferred and a warning is logged.
123 Problems and transactions are logged to syslogd(8) or postlogd(8).
125 Corrupted message files are marked so that the queue manager can move
126 them to the corrupt queue afterwards.
127 Depending on the setting of the notify_classes parameter, the postmas‐
129 ter is notified of bounces and of other trouble.
130
132 This delivery agent supports address extensions in email addresses and
133 in lookup table keys, but does not propagate address extension informa‐
134 tion to the result of table lookup.
135 Postfix should have lookup tables that can return multiple result at‐
137 tributes. In order to avoid the inconvenience of maintaining three ta‐
138 bles, use an LDAP or MYSQL database.
139
141 Changes to main.cf are picked up automatically, as virtual(8) processes
142 run for only a limited amount of time. Use the command "postfix reload"
143 to speed up a change.
144 The text below provides only a parameter summary. See postconf(5) for
146 more details including examples.
147
149 virtual_mailbox_base (empty)
150 A prefix that the virtual(8) delivery agent prepends to all
151 pathname results from $virtual_mailbox_maps table lookups.
152 virtual_mailbox_maps (empty)
154 Optional lookup tables with all valid addresses in the domains
155 that match $virtual_mailbox_domains.
156 virtual_minimum_uid (100)
158 The minimum user ID value that the virtual(8) delivery agent ac‐
159 cepts as a result from $virtual_uid_maps table lookup.
160 virtual_uid_maps (empty)
162 Lookup tables with the per-recipient user ID that the virtual(8)
163 delivery agent uses while writing to the recipient's mailbox.
164 virtual_gid_maps (empty)
166 Lookup tables with the per-recipient group ID for virtual(8)
167 mailbox delivery.
168 Available in Postfix version 2.0 and later:
170 virtual_mailbox_domains ($virtual_mailbox_maps)
172 Postfix is the final destination for the specified list of do‐
173 mains; mail is delivered via the $virtual_transport mail deliv‐
174 ery transport.
175 virtual_transport (virtual)
177 The default mail delivery transport and next-hop destination for
178 final delivery to domains listed with $virtual_mailbox_domains.
179 Available in Postfix version 2.5.3 and later:
181 strict_mailbox_ownership (yes)
183 Defer delivery when a mailbox file is not owned by its recipi‐
184 ent.
185
187 virtual_mailbox_lock (see 'postconf -d' output)
188 How to lock a UNIX-style virtual(8) mailbox before attempting
189 delivery.
190 deliver_lock_attempts (20)
192 The maximal number of attempts to acquire an exclusive lock on a
193 mailbox file or bounce(8) logfile.
194 deliver_lock_delay (1s)
196 The time between attempts to acquire an exclusive lock on a
197 mailbox file or bounce(8) logfile.
198 stale_lock_time (500s)
200 The time after which a stale exclusive mailbox lockfile is re‐
201 moved.
202
204 virtual_mailbox_limit (51200000)
205 The maximal size in bytes of an individual virtual(8) mailbox or
206 maildir file, or zero (no limit).
207 Implemented in the qmgr(8) daemon:
209 virtual_destination_concurrency_limit ($default_destination_concur‐
211 rency_limit)
212 The maximal number of parallel deliveries to the same destina‐
213 tion via the virtual message delivery transport.
214 virtual_destination_recipient_limit ($default_destination_recipi‐
216 ent_limit)
217 The maximal number of recipients per message for the virtual
218 message delivery transport.
219
221 config_directory (see 'postconf -d' output)
222 The default location of the Postfix main.cf and master.cf con‐
223 figuration files.
224 daemon_timeout (18000s)
226 How much time a Postfix daemon process may take to handle a re‐
227 quest before it is terminated by a built-in watchdog timer.
228 delay_logging_resolution_limit (2)
230 The maximal number of digits after the decimal point when log‐
231 ging sub-second delay values.
232 ipc_timeout (3600s)
234 The time limit for sending or receiving information over an in‐
235 ternal communication channel.
236 max_idle (100s)
238 The maximum amount of time that an idle Postfix daemon process
239 waits for an incoming connection before terminating voluntarily.
240 max_use (100)
242 The maximal number of incoming connections that a Postfix daemon
243 process will service before terminating voluntarily.
244 process_id (read-only)
246 The process ID of a Postfix command or daemon process.
247 process_name (read-only)
249 The process name of a Postfix command or daemon process.
250 queue_directory (see 'postconf -d' output)
252 The location of the Postfix top-level queue directory.
253 syslog_facility (mail)
255 The syslog facility of Postfix logging.
256 syslog_name (see 'postconf -d' output)
258 A prefix that is prepended to the process name in syslog
259 records, so that, for example, "smtpd" becomes "prefix/smtpd".
260 Available in Postfix version 3.0 and later:
262 virtual_delivery_status_filter ($default_delivery_status_filter)
264 Optional filter for the virtual(8) delivery agent to change the
265 delivery status code or explanatory text of successful or unsuc‐
266 cessful deliveries.
267 Available in Postfix version 3.3 and later:
269 enable_original_recipient (yes)
271 Enable support for the original recipient address after an ad‐
272 dress is rewritten to a different address (for example with
273 aliasing or with canonical mapping).
274 service_name (read-only)
276 The master.cf service name of a Postfix daemon process.
277 Available in Postfix 3.5 and later:
279 info_log_address_format (external)
281 The email address form that will be used in non-debug logging
282 (info, warning, etc.).
283
285 qmgr(8), queue manager
286 bounce(8), delivery status reports
287 postconf(5), configuration parameters
288 postlogd(8), Postfix logging
289 syslogd(8), system logging
290
292 Use "postconf readme_directory" or
293 "postconf html_directory" to locate this information.
294 VIRTUAL_README, domain hosting howto
295
297 The Secure Mailer license must be distributed with this software.
298
300 This delivery agent was originally based on the Postfix local delivery
301 agent. Modifications mainly consisted of removing code that either was
302 not applicable or that was not safe in this context: aliases,
303 ~user/.forward files, delivery to "|command" or to /file/name.
304 The Delivered-To: message header appears in the qmail system by Daniel
306 Bernstein.
307 The maildir structure appears in the qmail system by Daniel Bernstein.
309
311 Wietse Venema
312 IBM T.J. Watson Research
313 P.O. Box 704
314 Yorktown Heights, NY 10598, USA
315 Wietse Venema
317 Google, Inc.
318 111 8th Avenue
319 New York, NY 10011, USA
320 Andrew McNamara
322 andrewm@connect.com.au
323 connect.com.au Pty. Ltd.
324 Level 3, 213 Miller St
325 North Sydney 2060, NSW, Australia
326 VIRTUAL(8)