...for what the postman brings. Remember when we used to complain about paper spam? The Universe invented email spam to punish us for that.

I've tried to install spam filters on my email server, but it's a nightmare. They're Bayesian filters, and need to be taught by feeding them examples of good email to compare against bad email. I can see how it could work on an individual basis, but what do you do if you're running an email server whose users include lots of individuals and businesses? One man's junk mail is the lifeblood of another's business, and the false-positive rate of any content-based filter is too dangerously high. I have to answer people who only grumble about spam, but will rip my head off if a spam filter causes them to miss a message.

I just don't think that trying to filter spam through semantic analysis has any longterm future. The spammers have gotten agile, and they treat the problem like spread-spectrum communications: Constantly make minor changes to the content, personalize/randomize each message if possible, and try to dance around the opposing spam filter's centerspot. I get so much spam each day, I can watch the mutation in action, and I see spammers now varying their messages on a daily basis.

Nope, spam filters are a patch on a broken technology.