email, spam, filters

[Tuttle]

Originally posted by cwg01
True, the method WILL reject valid and legit emails because the legit is being served from the same ISP that a spammer uses

It depends what you're blocking on. You can stop a substantial amount of spam just by blocking open relay servers with a list like ORDB and have virtually no false positives (people who send legit mail tend to fix their open relays pretty quickly; the ones which stick around are run by people who don't use them anyway).

There's also a fantastic list (~3MB usually) at http://basic.wirehub.nl/spamlist-extended.txt full of sender email addresses to block. We download that once a day at work and get quite a few kills from it. Only issue I've had is that they block mass-mailing places like DoubleClick Dartmail and Microsoft bCentral, and believe it or not a few legit companies use those too. Still not much whitelisting involved.

For the more agressive approach there are lists like SPEWS and SpamCop. That sort of list is high in collateral damage. So if you don't want to block legit mail, don't use them.