I never thought to be a submitter to SpamCop, now I see why to do so.

Spammers don't like to be hassled. They are like any other red-blooded scumbag, they want to get maximum return for minimum investment. That's why they don't want to send to "Tarpits" or to people that report to sites like Spamcop.net.

Well, I don't have time to set up a tarpit right now, so I guess the next best thing is going to be to get blacklisted by spammers.

Update: I've recently been getting a lot of delivery failure receipts as well. These delivery receipts generally have the original headers in them. If you can grab those headers and add them to sites like Spamcop, you don't just reduce spam, you reduce the number of spammers that are using your name to send spam!