Just kidding - some of the ISPs offer SPAM stoppers, but they are flaky at best and tend to block some valid mail. As soon as they find they are being blocked, spammers tend to change the way their stuff presents itself and they are back in business again. About the only way to ensure you don't get spam would be to set up your email program to "allow only" the senders you wanted to receive from.
LOL. I, uh, have no idea.
I'm not sure how it works but I think Bill Clinton has been using one. He looks much taller than before.