aliases - Postfix local alias database format
The aliases(5) table provides a system-wide mechanism to
redirect mail for local recipients. The redirections are
processed by the Postfix local(8) delivery agent.
Normally, the aliases(5) table is specified as a text file
that serves as input to the postalias(1) command. The
result, an indexed file in dbm or db format, is used for
fast lookup by the mail system. Execute the command
newaliases in order to rebuild the indexed file after
changing the Postfix alias database.
The input and output file formats are expected to be com-
patible with Sendmail version 8, and are expected to be
suitable for the use as NIS maps.
Users can control delivery of their own mail by setting up
.forward files in their home directory. Lines in per-user
.forward files have the same syntax as the right-hand side
of aliases(5) entries.
The format of the alias database input file is as follows:
o An alias definition has the form
name: value1, value2, ...
o Empty lines and whitespace-only lines are ignored,
as are lines whose first non-whitespace character
is a `#'.
o A logical line starts with non-whitespace text. A
line that starts with whitespace continues a logi-
The name is a local address (no domain part). Use double
quotes when the name contains any special characters such
as whitespace, `#', `:', or `@'. The name is folded to
lowercase, in order to make database lookups case insensi-
In addition, when an alias exists for owner-name, delivery
diagnostics are directed to that address, instead of to
the originator of the message. This is typically used to
direct delivery errors to the maintainer of a mailing
list, who is in a better position to deal with mailing
list delivery problems than the originator of the undeliv-
The value contains one or more of the following:
Mail is forwarded to address, which is compatible
with the RFC 822 standard.
Mail is appended to /file/name. See local(8) for
details of delivery to file. Delivery is not lim-
ited to regular files. For example, to dispose of
unwanted mail, deflect it to /dev/null.
Mail is piped into command. Commands that contain
special characters, such as whitespace, should be
enclosed between double quotes. See local(8) for
details of delivery to command.
When the command fails, a limited amount of command
output is mailed back to the sender. The file
/usr/include/sysexits.h defines the expected exit
status codes. For example, use |"exit 67" to simu-
late a "user unknown" error, and |"exit 0" to
implement an expensive black hole.
Mail is sent to the destinations listed in the
named file. Lines in :include: files have the same
syntax as the right-hand side of alias entries.
A destination can be any destination that is
described in this manual page. However, delivery to
"|command" and /file/name is disallowed by default.
To enable, edit the allow_mail_to_commands and
allow_mail_to_files configuration parameters.
When alias database search fails, and the recipient local-
part contains the optional recipient delimiter (e.g.,
user+foo), the search is repeated for the unextended
address (e.g., user).
The propagate_unmatched_extensions parameter controls
whether an unmatched address extension (+foo) is propa-
gated to the result of table lookup.
The local(8) delivery agent always folds the search string
to lowercase before database lookup.
The local(8) delivery agent disallows regular expression
substitution of $1 etc. in alias_maps, because that would
open a security hole.
The local(8) delivery agent will silently ignore requests
to use the proxymap(8) server within alias_maps. Instead
it will open the table directly. Before Postfix version
2.2, the local(8) delivery agent will terminate with a
The following main.cf parameters are especially relevant.
The text below provides only a parameter summary. See
postconf(5) for more details including examples.
List of alias databases that are updated by the
List of alias databases queried by the local(8)
Restrict the usage of mail delivery to external
Restrict the usage of mail delivery to external
When delivering to an alias that has an owner- com-
panion alias, set the envelope sender address to
the right-hand side of the owner alias, instead
using of the left-hand side address.
A list of address rewriting or forwarding mecha-
nisms that propagate an address extension from the
original address to the result. Specify zero or
more of canonical, virtual, alias, forward,
include, or generic.
Give special treatment to owner-listname and list-
Delimiter that separates recipients from address
Available in Postfix version 2.3 and later:
Update the local(8) delivery agent's Delivered-To:
address (see prepend_delivered_header) only once,
at the start of a delivery; do not update the
Delivered-To: address while expanding aliases or
RFC 822 (ARPA Internet Text Messages)
local(8), local delivery agent
newaliases(1), create/update alias database
postalias(1), create/update alias database
postconf(5), configuration parameters
DATABASE_README, Postfix lookup table overview
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