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, patterns are tried in the order as
77 listed below:
78 user@domain address, address, ...
80 Redirect mail for user@domain to address. This form has the
81 highest precedence.
82 user address, address, ...
84 Redirect mail for user@site to address when site is equal to
85 $myorigin, when site is listed in $mydestination, or when it is
86 listed in $inet_interfaces or $proxy_interfaces.
87 This functionality overlaps with functionality of the local
89 aliases(5) database. The difference is that virtual(5) mapping
90 can be applied to non-local addresses.
91 @domain address, address, ...
93 Redirect mail for other users in domain to address. This form
94 has the lowest precedence.
95 Note: @domain is a wild-card. With this form, the Postfix SMTP
97 server accepts mail for any recipient in domain, regardless of
98 whether that recipient exists. This may turn your mail system
99 into a backscatter source: Postfix first accepts mail for non-
100 existent recipients and then tries to return that mail as "unde‐
101 liverable" to the often forged sender address.
102
104 The lookup result is subject to address rewriting:
105 · When the result has the form @otherdomain, the result becomes
107 the same user in otherdomain. This works only for the first
108 address in a multi-address lookup result.
109 · When "append_at_myorigin=yes", append "@$myorigin" to addresses
111 without "@domain".
112 · When "append_dot_mydomain=yes", append ".$mydomain" to addresses
114 without ".domain".
115
117 When a mail address localpart contains the optional recipient delimiter
118 (e.g., user+foo@domain), the lookup order becomes: user+foo@domain,
119 user@domain, user+foo, user, and @domain.
120 The propagate_unmatched_extensions parameter controls whether an
122 unmatched address extension (+foo) is propagated to the result of table
123 lookup.
124
126 Besides virtual aliases, the virtual alias table can also be used to
127 implement virtual alias domains. With a virtual alias domain, all
128 recipient addresses are aliased to addresses in other domains.
129 Virtual alias domains are not to be confused with the virtual mailbox
131 domains that are implemented with the Postfix virtual(8) mail delivery
132 agent. With virtual mailbox domains, each recipient address can have
133 its own mailbox.
134 With a virtual alias domain, the virtual domain has its own user name
136 space. Local (i.e. non-virtual) usernames are not visible in a virtual
137 alias domain. In particular, local aliases(5) and local mailing lists
138 are not visible as localname@virtual-alias.domain.
139 Support for a virtual alias domain looks like:
141 /etc/postfix/main.cf:
143 virtual_alias_maps = hash:/etc/postfix/virtual
144 Note: some systems use dbm databases instead of hash. See the output
146 from "postconf -m" for available database types.
147 /etc/postfix/virtual:
149 virtual-alias.domain anything (right-hand content does not matter)
150 postmaster@virtual-alias.domain postmaster
151 user1@virtual-alias.domain address1
152 user2@virtual-alias.domain address2, address3
153 The virtual-alias.domain anything entry is required for a virtual alias
155 domain. Without this entry, mail is rejected with "relay access
156 denied", or bounces with "mail loops back to myself".
157 Do not specify virtual alias domain names in the main.cf mydestination
159 or relay_domains configuration parameters.
160 With a virtual alias domain, the Postfix SMTP server accepts mail for
162 known-user@virtual-alias.domain, and rejects mail for unknown-user@vir‐
163 tual-alias.domain as undeliverable.
164 Instead of specifying the virtual alias domain name via the vir‐
166 tual_alias_maps table, you may also specify it via the main.cf vir‐
167 tual_alias_domains configuration parameter. This latter parameter uses
168 the same syntax as the main.cf mydestination configuration parameter.
169
171 This section describes how the table lookups change when the table is
172 given in the form of regular expressions. For a description of regular
173 expression lookup table syntax, see regexp_table(5) or pcre_table(5).
174 Each pattern is a regular expression that is applied to the entire
176 address being looked up. Thus, user@domain mail addresses are not bro‐
177 ken up into their user and @domain constituent parts, nor is user+foo
178 broken up into user and foo.
179 Patterns are applied in the order as specified in the table, until a
181 pattern is found that matches the search string.
182 Results are the same as with indexed file lookups, with the additional
184 feature that parenthesized substrings from the pattern can be interpo‐
185 lated as $1, $2 and so on.
186
188 This section describes how the table lookups change when lookups are
189 directed to a TCP-based server. For a description of the TCP
190 client/server lookup protocol, see tcp_table(5). This feature is not
191 available up to and including Postfix version 2.4.
192 Each lookup operation uses the entire address once. Thus, user@domain
194 mail addresses are not broken up into their user and @domain con‐
195 stituent parts, nor is user+foo broken up into user and foo.
196 Results are the same as with indexed file lookups.
198
200 The table format does not understand quoting conventions.
201
203 The following main.cf parameters are especially relevant to this topic.
204 See the Postfix main.cf file for syntax details and for default values.
205 Use the "postfix reload" command after a configuration change.
206 virtual_alias_maps
208 List of virtual aliasing tables.
209 virtual_alias_domains
211 List of virtual alias domains. This uses the same syntax as the
212 mydestination parameter.
213 propagate_unmatched_extensions
215 A list of address rewriting or forwarding mechanisms that propa‐
216 gate an address extension from the original address to the
217 result. Specify zero or more of canonical, virtual, alias, for‐
218 ward, include, or generic.
219 Other parameters of interest:
221 inet_interfaces
223 The network interface addresses that this system receives mail
224 on. You need to stop and start Postfix when this parameter
225 changes.
226 mydestination
228 List of domains that this mail system considers local.
229 myorigin
231 The domain that is appended to any address that does not have a
232 domain.
233 owner_request_special
235 Give special treatment to owner-xxx and xxx-request addresses.
236 proxy_interfaces
238 Other interfaces that this machine receives mail on by way of a
239 proxy agent or network address translator.
240
242 cleanup(8), canonicalize and enqueue mail
243 postmap(1), Postfix lookup table manager
244 postconf(5), configuration parameters
245 canonical(5), canonical address mapping
246
248 Use "postconf readme_directory" or "postconf html_directory" to locate
249 this information.
250 ADDRESS_REWRITING_README, address rewriting guide
251 DATABASE_README, Postfix lookup table overview
252 VIRTUAL_README, domain hosting guide
253
255 The Secure Mailer license must be distributed with this software.
256
258 Wietse Venema
259 IBM T.J. Watson Research
260 P.O. Box 704
261 Yorktown Heights, NY 10598, USA
262 VIRTUAL(5)