Not only do Bayesian filter out some legitimate mail, the spam mills particularly target the Bayesian algorithms with deliberate misspellings. Mail washer with the option to highlight mail from known open relays and known spam DNSs before downloading from the server keeps my network spam free and helps reduce mal-ware intrusions. There are additional spam reporting options, Spamcop and Blue frog. Spam cop doesn’t seem to do much except bolt the stable door after the horse etc. etc. I've just started trial in the new link to Blue Frog, a system for mass posting of opt out requests to "encourage" spammers to cleanse their address lists of Blue Frog Users. No noticeable change in spam at the server, still 3-5 a day.
I 'm pretty certain that my address got harvested because of the habit many people have piling all the addresses in to the “To” field. Mail program providers could help by enabling the “BCC” field as a default rather than the user having to hunt through options tabs to enable it.
With mail washer, I still make a visual check before downloading. It's not a cure but a damn good pro tem spam laxative.