Книга: Linux Network Administrator Guide, Second Edition

Alias Files

Alias Files

Exim is able to handle alias files compatible with Berkeley's sendmail alias files. Entries in the alias file can have the following form:

alias: recipients

recipients is a comma-separated list of addresses that will be substituted for the alias. The recipient list may be continued across newlines if the next line begins with whitespace.

A special feature allows Exim to handle mailing lists that are held separately from the alias file: if you specify:include: filename as a recipient, Exim reads the specified file and substitutes its contents as a list of recipients. An alternative to handling mailing lists is shown later in this chapter in "Mailing Lists".

The main aliases file is /etc/aliases. If you make this file world-writable or group-writeable, Exim will refuse to use it and will defer local deliveries. You can control the test it applies to the file's permissions by setting modemask in the system_aliases director.

This is a sample aliases file:

# vbrew.com /etc/aliases file
hostmaster: janet
postmaster: janet
usenet: phil
# The development mailing list.
development: joe, sue, mark, biff,
 /var/mail/log/development
owner-development: joe
# Announcements of general interest are mailed to all
# of the staff
announce::include: /etc/Exim/staff,
 /var/mail/log/announce
owner-announce: root
# gate the ppp mailing list to a local newsgroup
ppp-list: "|/usr/local/bin/gateit local.lists.ppp"

When there are file names and pipe commands in an alias file, as here, Exim needs to be told which userid to run the deliveries under. The user option (and possibly group, too) must be set in Exim's configuration file, either on the director that is handling the aliases, or on the transports to which it directs these items.

If an error occurs while delivering to an address generated from the aliases file, Exim will send a bounce message to the sender of the message, as usual, but this might not be appropriate. The errors_to option can be used to specify that bounce messages are to be sent elsewhere; for example, to the postmaster.

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