.\"	$OpenBSD: aliases.5,v 1.4 2012/09/14 17:35:27 jmc Exp $
.\"
.\" Copyright (c) 2012 Gilles Chehade <gilles@openbsd.org>
.\"
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.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
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.Dd $Mdocdate: September 14 2012 $
.Dt ALIASES 5
.Os
.Sh NAME
.Nm aliases
.Nd aliases file for smtpd
.Sh SYNOPSIS
.Nm aliases
.Sh DESCRIPTION
This manual page describes the format of the
.Nm
file, as used by
.Xr smtpd 8 .
An alias in its simplest form is used to assign an arbitrary name
to an email address, or a group of email addresses.
This provides a convenient way to send mail.
For example an alias could refer to all users of a group:
email to that alias would be sent to all members of the group.
Much more complex aliases can be defined however:
an alias can refer to other aliases,
be used to send mail to a file instead of another person,
or to execute various commands.
.Pp
Within the file,
.Ql #
is a comment delimiter; anything placed after it is discarded.
The file consists of key/value mappings of the form:
.Bd -filled -offset indent
key: value1, value2, value3, ...
.Ed
.Pp
.Em key
is always folded to lowercase before alias lookups to ensure that
there can be no ambiguity.
The key is expanded to the corresponding values,
which consist of one or more of the following:
.Bl -tag -width Ds
.It Em user
A user on the host machine.
The user must have a valid entry in the
.Xr passwd 5
database file.
.It Ar /path/to/file
Append messages to
.Ar file ,
specified by its absolute pathname.
.It \*(Ba Ns Ar command
Pipe the message to
.Ar command
on its standard input.
The command is run under the privileges of the daemon's unprivileged account.
.It No : Ns Ar include : Ns Ar /path/to/file
Include any definitions in
.Ar file
as alias entries.
The format of the file is identical to this one.
.It Ar user-part@domain-part
An email address in RFC 5322 format
(see
.Xr mailaddr 7 ) .
If an address extension is appended to the user-part,
it is stripped so that an address such as user+ext@example.com
will only use the part that precedes
.Sq +
as a
.Em key .
.El
.Sh FILES
.Bl -tag -width "/etc/mail/aliasesXXX"
.It Pa /etc/mail/aliases
Default
.Nm
file.
.El
.Sh SEE ALSO
.Xr smtpd.conf 5 ,
.Xr makemap 8 ,
.Xr newaliases 8 ,
.Xr smtpd 8
.Sh HISTORY
The
.Nm
file format appeared in
.Bx 4.0 .