I'm curious what others regard as a good "SPAM" filter, to work with POP3 (i.e. - Outlook Express, Thunderbird, etc.) along with commercial anti-virus programs (NOD, KAV, etc.). I'm currently using SpamKiller from McAfee (as part of the McAfee ISS), but that subscription will be expiring soon - thankfully! SpamKiller is NOT very good at all, often filtering EXPECTED emails, while allowing in obvious junk. For a program that updates itself almost daily, I'd expect better! So is there a free one that others would recommend, and have had good experiences with?