July 2001
Intermediate to advanced
640 pages
18h 9m
English
Content preview from Exim: The Mail Transfer AgentBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Chapter 14. Rewriting Addresses
There are a number of circumstances in which addresses in messages are altered as they are handled by Exim. This can apply both to the messages’ envelopes and to their headers. The header lines that may be affected are Bcc:, Cc:, From:, Reply-To:, Sender:, and To:. Some of these changes happen automatically, whereas others are explicitly configured by the administrator.
Automatic Rewriting
One case of automatic rewriting is the addition of a domain to an unqualified
address, as discussed in
Chapter 13. This qualification is applied
to addresses in header lines as well as to those in envelopes. For example, if
a message is sent on a host where qualify_domain is set to crete.example
by this command:
$ exim daedalus To: daedalus ...
the unqualified local part daedalus is transformed into the fully qualified
address daedalus@crete.example, both in the envelope and in the To:
header line. Messages that arrive from other hosts should not contain
unqualified addresses; you need to set sender_unqualified_hosts and/or
receiver_unqualified_hosts if you want to allow such messages to be
accepted (as described in
Chapter 13).
The other case in which automatic rewriting happens is when an incomplete domain is given. The routing process may cause this to be expanded into the full domain name within the current encompassing domain. For example, a header such as:
To: minos@knossos
might be rewritten as:
To: minos@knossos.crete.example
if encountered on a host within the ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.