Filter Spam Using ISP-Supplied Junk Mail Headers

Interpretation, says Nietzsche, is what the will to power does. Of course, Nietzsche can easily interpret everything along this interpretation.
I'm just name-dropping, though, limpidly attempting to depict the interpretation of mail as spam a power that you can have, if you will:
Maybe your Internet Service Provider runs a spam filter that changes messages subtly if it believes they are junk. Here's how to make use of this simple yet effective line of spam defense.