I have BrightMail filtering on the mail server, which works pretty well, but it relies on a technical definition of spam. It isn't free.

As an individual, to run on my mail client, I really like Cloudmark's SpamNet. Rather than relying on a technical definition of spam, when emails arrive, users elect to block mail that hasn't been filtered, thus, some mailing lists get added (usually because recipients didn't knowingly opt-in). You can always elect to receive mail, so your own personal settings trump the democratically determined ones. SpamNet catches about 95%. I would say Brightmail gets about 85%. I think that SpamNet, for an individual, is about $4 a month. I don't know what kind of deal they offer for corporations.

Brightmail is not available for individuals. The mail server ties into it to evaluate spam. I don't know what the cost on the mail server's performance is.

>>Hi. Does anyone have suggestions on Anti-Spam software?
>
>Hello Randy,
>
>I don't know if this can help you but we have just completed the first draft version of a basic, brute-force SPAM Blocker in VFP.
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>We use it to block most of the emails that are landing in our mail server and, even in its very basic state, it successfully blocks more than 80% of the usual SPAM we receive.
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>The thing is Open Source and ABSOLUTELY free: SPAM Blocker
>
>Pat