As a naive barely-programmer, I assume this is possible - I would look for an algorithm to without fail identify spam from genuine emails, and when I was kicked out I would give it free of charge to every email provider in the world.
I would also run everybody's multislice simulations, starting with my several-billion-atom one that would otherwise need silly amounts of breaking up to do a bit at a time on CamGRID.
I fear the spam problem is another AI-complete one. You could search for a program which correctly classified everything in a ginormous input corpus, but it could very easily turn out to be distinguishing on the wrong attributes and fail the first time it saw a mail that wasn't part of the corpus. Also, the problem with spam is that it evolves; once the algorithm was running on all mail systems, spammers would have a copy to test against and could hammer on it looking for a way through...
I would also run everybody's multislice simulations, starting with my several-billion-atom one that would otherwise need silly amounts of breaking up to do a bit at a time on CamGRID.