1VIRTUAL(5) File Formats Manual VIRTUAL(5)
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6 virtual - Postfix virtual alias table format
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9 postmap /etc/postfix/virtual
10 postmap -q "string" /etc/postfix/virtual
12 postmap -q - /etc/postfix/virtual <inputfile
14
16 The optional virtual(5) alias table rewrites recipient addresses for
17 all local, all virtual, and all remote mail destinations. This is
18 unlike the aliases(5) table which is used only for local(8) delivery.
19 Virtual aliasing is recursive, and is implemented by the Postfix
20 cleanup(8) daemon before mail is queued.
21 The main applications of virtual aliasing are:
23 · To redirect mail for one address to one or more addresses.
25 · To implement virtual alias domains where all addresses are
27 aliased to addresses in other domains.
28 Virtual alias domains are not to be confused with the virtual
30 mailbox domains that are implemented with the Postfix virtual(8)
31 mail delivery agent. With virtual mailbox domains, each recipi‐
32 ent address can have its own mailbox.
33 Virtual aliasing is applied only to recipient envelope addresses, and
35 does not affect message headers. Use canonical(5) mapping to rewrite
36 header and envelope addresses in general.
37 Normally, the virtual(5) alias table is specified as a text file that
39 serves as input to the postmap(1) command. The result, an indexed file
40 in dbm or db format, is used for fast searching by the mail system.
41 Execute the command "postmap /etc/postfix/virtual" to rebuild an
42 indexed file after changing the corresponding text file.
43 When the table is provided via other means such as NIS, LDAP or SQL,
45 the same lookups are done as for ordinary indexed files.
46 Alternatively, the table can be provided as a regular-expression map
48 where patterns are given as regular expressions, or lookups can be
49 directed to TCP-based server. In those case, the lookups are done in a
50 slightly different way as described below under "REGULAR EXPRESSION
51 TABLES" or "TCP-BASED TABLES".
52
54 The search string is folded to lowercase before database lookup. As of
55 Postfix 2.3, the search string is not case folded with database types
56 such as regexp: or pcre: whose lookup fields can match both upper and
57 lower case.
58
60 The input format for the postmap(1) command is as follows:
61 pattern result
63 When pattern matches a mail address, replace it by the corre‐
64 sponding result.
65 blank lines and comments
67 Empty lines and whitespace-only lines are ignored, as are lines
68 whose first non-whitespace character is a `#'.
69 multi-line text
71 A logical line starts with non-whitespace text. A line that
72 starts with whitespace continues a logical line.
73
75 With lookups from indexed files such as DB or DBM, or from networked
76 tables such as NIS, LDAP or SQL, each user@domain query produces a
77 sequence of query patterns as described below.
78 Each query pattern is sent to each specified lookup table before trying
80 the next query pattern, until a match is found.
81 user@domain address, address, ...
83 Redirect mail for user@domain to address. This form has the
84 highest precedence.
85 user address, address, ...
87 Redirect mail for user@site to address when site is equal to
88 $myorigin, when site is listed in $mydestination, or when it is
89 listed in $inet_interfaces or $proxy_interfaces.
90 This functionality overlaps with functionality of the local
92 aliases(5) database. The difference is that virtual(5) mapping
93 can be applied to non-local addresses.
94 @domain address, address, ...
96 Redirect mail for other users in domain to address. This form
97 has the lowest precedence.
98 Note: @domain is a wild-card. With this form, the Postfix SMTP
100 server accepts mail for any recipient in domain, regardless of
101 whether that recipient exists. This may turn your mail system
102 into a backscatter source: Postfix first accepts mail for non-
103 existent recipients and then tries to return that mail as "unde‐
104 liverable" to the often forged sender address.
105
107 The lookup result is subject to address rewriting:
108 · When the result has the form @otherdomain, the result becomes
110 the same user in otherdomain. This works only for the first
111 address in a multi-address lookup result.
112 · When "append_at_myorigin=yes", append "@$myorigin" to addresses
114 without "@domain".
115 · When "append_dot_mydomain=yes", append ".$mydomain" to addresses
117 without ".domain".
118
120 When a mail address localpart contains the optional recipient delimiter
121 (e.g., user+foo@domain), the lookup order becomes: user+foo@domain,
122 user@domain, user+foo, user, and @domain.
123 The propagate_unmatched_extensions parameter controls whether an
125 unmatched address extension (+foo) is propagated to the result of table
126 lookup.
127
129 Besides virtual aliases, the virtual alias table can also be used to
130 implement virtual alias domains. With a virtual alias domain, all
131 recipient addresses are aliased to addresses in other domains.
132 Virtual alias domains are not to be confused with the virtual mailbox
134 domains that are implemented with the Postfix virtual(8) mail delivery
135 agent. With virtual mailbox domains, each recipient address can have
136 its own mailbox.
137 With a virtual alias domain, the virtual domain has its own user name
139 space. Local (i.e. non-virtual) usernames are not visible in a virtual
140 alias domain. In particular, local aliases(5) and local mailing lists
141 are not visible as localname@virtual-alias.domain.
142 Support for a virtual alias domain looks like:
144 /etc/postfix/main.cf:
146 virtual_alias_maps = hash:/etc/postfix/virtual
147 Note: some systems use dbm databases instead of hash. See the output
149 from "postconf -m" for available database types.
150 /etc/postfix/virtual:
152 virtual-alias.domain anything (right-hand content does not matter)
153 postmaster@virtual-alias.domain postmaster
154 user1@virtual-alias.domain address1
155 user2@virtual-alias.domain address2, address3
156 The virtual-alias.domain anything entry is required for a virtual alias
158 domain. Without this entry, mail is rejected with "relay access
159 denied", or bounces with "mail loops back to myself".
160 Do not specify virtual alias domain names in the main.cf mydestination
162 or relay_domains configuration parameters.
163 With a virtual alias domain, the Postfix SMTP server accepts mail for
165 known-user@virtual-alias.domain, and rejects mail for unknown-user@vir‐
166 tual-alias.domain as undeliverable.
167 Instead of specifying the virtual alias domain name via the vir‐
169 tual_alias_maps table, you may also specify it via the main.cf vir‐
170 tual_alias_domains configuration parameter. This latter parameter uses
171 the same syntax as the main.cf mydestination configuration parameter.
172
174 This section describes how the table lookups change when the table is
175 given in the form of regular expressions. For a description of regular
176 expression lookup table syntax, see regexp_table(5) or pcre_table(5).
177 Each pattern is a regular expression that is applied to the entire
179 address being looked up. Thus, user@domain mail addresses are not bro‐
180 ken up into their user and @domain constituent parts, nor is user+foo
181 broken up into user and foo.
182 Patterns are applied in the order as specified in the table, until a
184 pattern is found that matches the search string.
185 Results are the same as with indexed file lookups, with the additional
187 feature that parenthesized substrings from the pattern can be interpo‐
188 lated as $1, $2 and so on.
189
191 This section describes how the table lookups change when lookups are
192 directed to a TCP-based server. For a description of the TCP
193 client/server lookup protocol, see tcp_table(5). This feature is not
194 available up to and including Postfix version 2.4.
195 Each lookup operation uses the entire address once. Thus, user@domain
197 mail addresses are not broken up into their user and @domain con‐
198 stituent parts, nor is user+foo broken up into user and foo.
199 Results are the same as with indexed file lookups.
201
203 The table format does not understand quoting conventions.
204
206 The following main.cf parameters are especially relevant to this topic.
207 See the Postfix main.cf file for syntax details and for default values.
208 Use the "postfix reload" command after a configuration change.
209 virtual_alias_maps
211 List of virtual aliasing tables.
212 virtual_alias_domains
214 List of virtual alias domains. This uses the same syntax as the
215 mydestination parameter.
216 propagate_unmatched_extensions
218 A list of address rewriting or forwarding mechanisms that propa‐
219 gate an address extension from the original address to the
220 result. Specify zero or more of canonical, virtual, alias, for‐
221 ward, include, or generic.
222 Other parameters of interest:
224 inet_interfaces
226 The network interface addresses that this system receives mail
227 on. You need to stop and start Postfix when this parameter
228 changes.
229 mydestination
231 List of domains that this mail system considers local.
232 myorigin
234 The domain that is appended to any address that does not have a
235 domain.
236 owner_request_special
238 Give special treatment to owner-xxx and xxx-request addresses.
239 proxy_interfaces
241 Other interfaces that this machine receives mail on by way of a
242 proxy agent or network address translator.
243
245 cleanup(8), canonicalize and enqueue mail
246 postmap(1), Postfix lookup table manager
247 postconf(5), configuration parameters
248 canonical(5), canonical address mapping
249
251 Use "postconf readme_directory" or "postconf html_directory" to locate
252 this information.
253 ADDRESS_REWRITING_README, address rewriting guide
254 DATABASE_README, Postfix lookup table overview
255 VIRTUAL_README, domain hosting guide
256
258 The Secure Mailer license must be distributed with this software.
259
261 Wietse Venema
262 IBM T.J. Watson Research
263 P.O. Box 704
264 Yorktown Heights, NY 10598, USA
265 VIRTUAL(5)