For reducing spam I've had very good luck with Spam Assasin filters on the server side followed up with a well trained Thunderbird boolean logic filter on my mail client side. I get at least 300 spam email a day. Spam Assasin catches about half and my Thunderbird catches (automatically redirects them to my Junk folder) about 90% of what's left. As long as you don't set your Spam Assasin too aggressively and you properly train your boolean filter on your email client you can get the junk that makes it through down to spam levels you would have seen in 1999...and with NO false positives.