My provider uses Postini, and it blocks at least 95% of the Spam I would ordinarily get. I look every day or so to scan what is there ~~ messages can get snagged by Postini that you would want, but that hasn't happened to me in well over a year, maybe two years.

When I first started using it, I'd say about 4 messages from friends managed to run afoul of Postini. It is a simple task to add their addresses to the do not block list and everything they write will be delivered.   It is also easy to manually block addresses that slip by and go to your regular In Box in any quantity that you find irritating enough to do this.

I just checked ~~ The numbers are larger than I thought. I have manually approved 14 addresses and blocked 7 others. It does caution you that blocking spammers is usually ineffective since they change addresses so often.

The funniest one was the Newsletter from my provider that Postini tagged as Spam!