Spam blocking software

What do you guys recommend for spam blocking software?

Thanks,
David

Our firm has a firewall that protects our system from incoming spam - works most of the time.

If you want to get rid of those annoying popups while surfing the net, look at googles popup blocker, free download from google site. I have been using this for a few months now and already have nearly 2000 popups blocked!!!

anon