Josh wrote regarding 'Re: [SLE] Look for opinions: Best Email server w/ virtual domain and anti-spam functionaliy?' on Thu, Sep 09 at 21:18:
JW,
We use CommunigatePro (proprietary, but cheap) with SpamAssassin.
Communigate is fast and rock-solid if a bit no-frills, and supports the features you've mentioned. While SpamAssassin is open source and very sophisticated, it has one problem that has caused us a lot of difficulty: all spam processing is done entirely in RAM, with no ability to swap to disk if the server gets slammed.
SA doesn't do anything to lock itself in physical RAM. If the server's under high load and SA is scanning lots of messages, then the kernel can't very well swap it out, since SA will be receiving most of the available time slices. I'm not sure how the processing would work outside of RAM, anyway. What's it gonna do - write a file and then read the file off of the disk several times? :) If the memory usage is a problem, it'd probably be a good idea to take some of the rulesets out (or, more likely, look at other processes running on the same machine / install mroe memory). Get rid of the sets that rely on network connections (like the RBL lists) to speed the thing up. --Danny