Not really an answer to your question, but it is related.... a few years back I registered an account on Spamcop.net. It provides the option of forwarding the raw contents of the spam message to them and they filter out the relevant reporting addresses and allow you to complain to the mail provider and ISP for any websites linked in the message. I don't have a clue whether it has any effect, but there is something satisfying about being able to file a boilerplate complaint with a couple of clicks.