I have two favorites:
1. For Outlook mail (when you run Exchange Server): Disruptor OL, which I bought and installed
. It's an amazingly good spam filter and it catches almost everything!
Out of the 300 spams I get a day from being a domreg and a bunch of common names @ diginexus.com, I get very few now.
2. For home, I run Spam Eater Pro. Every 5 minutes, this keeps my Netaxs (same as vsp) shell and my Earthlink POP3 accounts clean and happy. This has about a 95% success rate, and catches the really nasty stuff.
I agree with VSP. I've only had my netaxs shell for 6 years, but it's getting over 40 spams a day. Spam Eater Pro keeps me sane.
It's a problem. And it's only going to get worse with the large amounts of people that put up open servers or workstations with Sendmail or IIS5 not configured correctly.
Mitch