I occasionally receive spam via MC, which I then forward to MC's abuse desk along with a polite note. Every time they have responded quickly and effectively.

I occasionally receive spam via MC, which I then forward to MC's abuse desk along with a polite note. Every time they have responded quickly and effectively. (Don't forget to tell them that their efforts are appreciated - they do a hard job, and they like attaboys.) It's why I don't blacklist MC; in my experience they are trustworthy, and bulk mail does have limited, legitimate use.