Книга: Linux Network Administrator Guide, Second Edition

Forwarding

Forwarding

Users can redirect their mail to alternative addresses by creating a .forward file in their home directories. This contains a list of recipients separated by commas and/or newlines. All lines of the file are read and interpreted. Any type of address may be used. A practical example of a .forward file for vacations might be:

janet, "|vacation"

In other descriptions of .forward files, you might see the username at the start preceded by a backslash. This was necessary in some older MTAs to stop a search for a .forward for the new name, which could lead to looping. The backslash is not necessary in Exim, which automatically avoids loops of this kind.[119] However, a backslash is permitted, and in fact it does make a difference in configurations where several domains are being handled at once. Without a backslash, an unqualified username is qualified with a default domain; with a backslash the incoming domain is preserved.

The first address in the forward file delivers the incoming message to janet's mailbox, while the vacation command returns a short notification to the sender.[120]

In addition to supporting "traditional" forwarding files, Exim can be configured to allow more complex files called filters. Instead of being just a list of forwarding addresses, a filter file can contain tests on the contents of the incoming message so that, for example, messages could be forwarded only if the subject contained the message "urgent." The system administrator must decide whether to allow users this flexibility.

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