ALIASES(5) ALIASES(5)
NAME
aliases - Postfix local alias database format
SYNOPSIS
newaliases
DESCRIPTION
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 compatible 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:
An alias definition has the form
name: value1, value2, ...
Empty lines and whitespace-only lines are ignored, as are lines whose first non-whitespace
character is a `#'.
A logical line starts with non-whitespace text. A line that starts with whitespace continues a
logical line.
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 insensitive.
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 undelivered mail.
The value contains one or more of the following:
address
Mail is forwarded to address, which is compatible with the RFC 822 standard.
/file/name
Mail is appended to /file/name. See local(8) for details of delivery to file. Delivery is not
limited to regular files. For example, to dispose of unwanted mail, deflect it to /dev/null.
|command
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 simulate a "user unknown" error, and "|exit 0" to implement an expensive black hole.
:include:/file/name
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_com-mands allow_mail_to_commands
mands and allow_mail_to_files configuration parameters.
ADDRESS EXTENSION
When alias database search fails, and the recipient localpart contains the optional recipient delim-iter delimiter
iter (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 propagated to the result of table lookup.
CASE FOLDING
The local(8) delivery agent always folds the search string to lowercase before database lookup.
SECURITY
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) deliv-ery delivery
ery agent will terminate with a fatal error.
CONFIGURATION PARAMETERS
The following main.cf parameters are especially relevant. The text below provides only a parameter
summary. See postconf(5) for more details including examples.
alias_database
List of alias databases that are updated by the newaliases(1) command.
alias_maps
List of alias databases queried by the local(8) delivery agent.
allow_mail_to_commands
Restrict the usage of mail delivery to external command.
allow_mail_to_files
Restrict the usage of mail delivery to external file.
expand_owner_alias
When delivering to an alias that has an owner- companion alias, set the envelope sender
address to the right-hand side of the owner alias, instead using of the left-hand side
address.
propagate_unmatched_extensions
A list of address rewriting or forwarding mechanisms that propagate an address extension from
the original address to the result. Specify zero or more of canonical, virtual, alias, for-ward, forward,
ward, include, or generic.
owner_request_special
Give special treatment to owner-listname and listname-request addresses.
recipient_delimiter
Delimiter that separates recipients from address extensions.
Available in Postfix version 2.3 and later:
frozen_delivered_to
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 .forward files.
STANDARDS
RFC 822 (ARPA Internet Text Messages)
SEE ALSO
local(8), local delivery agent
newaliases(1), create/update alias database
postalias(1), create/update alias database
postconf(5), configuration parameters
README FILES
Use "postconf readme_directory" or "postconf html_directory" to locate this information.
DATABASE_README, Postfix lookup table overview
LICENSE
The Secure Mailer license must be distributed with this software.
AUTHOR(S)
Wietse Venema
IBM T.J. Watson Research
P.O. Box 704
Yorktown Heights, NY 10598, USA
ALIASES(5)
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