Finally I see a solution to spam that I like.

I've never been a big fan of blacklists or whitelists, simply because they require too much work. Baysean filters work nice, but I really think that we needed a solution that restricts the senders; even if the filters filter out your message, there's an associated cost (bandwidth and such) in getting the message received.

Basically the new solution would require each e-mail to solve a crytopgraphic puzzle in your e-mail client for about 10-20 seconds. If it solved it, it would be granted a high priority (your e-mail client would have to download a patch that would support this new prioritizing method); if not, it would not be granted high priority.

Give the article a read and you can understand how it works. Good idea.