by I’ve set up a small test group of administrators to get their email filtered via MailScanner and spamassassin. I tuned MailScanner as little as possible.
Our goal is to delete 40% of spam. Going from no content filtering straight to a “drop email” system is a little intimidating.
My only false positives so far have come from automated tools: NCSU has a Matt’s Script Archive script that mailed me, and our calendar server emails people about schedule changes. I don’t know if blocking MSA scripts is OK, because I guess the reasoning is the programming is bad enough that people can use them for spam. I’m eventually going to whitelist all our domains, but for testing I want to see all the possible false positives.
The only other problem so far is that MailScanner blocks all multimedia in email by default.
MailScanner on a 2CPU/4Gb RAM machine seems to filter around 1.7 messages per second, on average–although I haven’t tuned it at all for performance. That’s OK, because we only need a maximum of 1 message/second filtering, but it’s kind of depressing.