If only that were true. I think it was around about the same time (2004) that Bill Gates said "Two years from now, spam will be solved". Of course the spammers

If only that were true. I think it was around about the same time (2004) that Bill Gates said "Two years from now, spam will be solved". Of course the spammers quickly adapted their techniques to defeat Bayesian filters, leading to the sender reputation based systems we have today (like Postini). When Google/Postini can't deliver my mail to my users I have a problem. When they can't deliver their own mail to their own users we all have a problem. But it's worse than that - any given recipient will be running a system with an unknown false positive rate, so email degenerates into a game of chance.