Exim

Exim is a powerful e-mail server. We have a few posts about it here.

Filtering spam with Exim and Spamassassin (properly)

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SpamAssassin is a frequently used companion for Exim. However, most people set it up in a synchronous manner – spam is checked directly when the SMTP session is opened. While this is certainly a valid technique, it has it’s drawbacks. It leaves the server vulnerable to DOS attacks because the spam filtering is a big resource hog. Having SpamAssassin headers in the mail from the remote servers is also an issue, because the $h_X-Spam-* variables will start misbehaving suddenly.

Fixing RDNS_NONE with Spamassassin

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When dealing with SpamAssassin and Exim, one may often encounter a mysterious RDNS_NONE

Filtering spam with Exim only

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Defense against spam has always been a hassle. Statistical filters only get you so far and they consume a LOT of resources. For exactly that reason I like to employ basic checking policies before accepting e-mail at all. These policies have gotten me pretty far and my false positive rate is pretty low.

The Big Exim Tutorial

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In September 2009 I created the big Exim tutorial consisting of 5 parts on the Hungarian Unix Portal. In January 2010, I transfered it to my Hungarian site. Now I’m translating it to English.