I just ran across SpamSlayer, which is a set of mail-filters for Mozilla that can apparently eliminate 80%-100% of Spam from your Inbox.
SpamSlayer is technically a “filter package”. It filters your email transparently and most spam never even reaches your inbox. Anything that looks like spam is directed into a separate “Possible Spam” folder for later review.
It looks interesting but, of course, I use SpamCop for my e-mail anyway. For just $30/year, SpamCop provides an account accessible via IMAP, POP3, or even webmail. And, through an extensive set of regular expressions, hardly any Spam gets into my Inbox. To top it off, SpamCop runs on Open Source software including as Apache, Perl, and MySQL — I highly recommend the service.
$30/ year for spamcop? You got jipped. I have an MIT account with access via POP, IMAP, Webmail, ssh with an number of clients etc, all completely without filters. I only pay $30,000/ year for it.