March 2004
Intermediate to advanced
248 pages
7h 18m
English
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Chapter 12. Virtual Domains
In qmail-speak, a virtual domain is one handled locally but with a different set of mailboxes from the home domain. Qmail’s virtual domain handling is one of its strongest features, thanks to a simple and clean design.
How Virtual Domains Work
Qmail turns addresses in a virtual domain into subaddresses of a local user, then handles the subaddressed message like any other local message. The translation from virtual to local addresses is in the control file virtualdomains. Assume, for example, that it contained the line:
myvirt.com:virtuser
Then mail addressed to marvin@myvirt.com is translated to virtuser-marvin, and then delivered normally. If there’s a user virtuser, it checks for ~virtuser/.qmail-marvin or ~virtuser/.qmail-default. If there’s no such user (which is often the case), the address is turned into alias-virtuser-marvin and delivered under the control of ~alias/.qmail-virtuser-marvin or ~alias/.qmail-virtuser-default or ~alias/.qmail-default.
When qmail translates the mailbox part of a virtual domain address, it does not change the domain. That is, in the previous example, marvin@myvirt.com is translated to virtuser-marvin@myvirt.com. This seems like a mistake, because this is not Marvin’s address, until you realize that the translated address is used only within qmail. The virtual domain remains with the address throughout the delivery process, so delivery programs can check $HOST or $RECIPIENT to tell whether a message was addressed to a virtual ...
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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.