I get email like that all the time.

"You have a secret admirer. Register an account with our service to see who it is." type of messages. Usually a match-making service that doesn't have enough info on me to know that I am married and not looking.

I don't bother replying, that is a sure way of them knowing that you have an active email account, and they will add it to their active list and sell it. I found that out the hard way when asking to be removed from lists actually gets my address on more lists and gets it sold. Hard to prove that, but I know it happens. Best thing I can think of is to fake a bounced email message right back to their working address and then they'll put you on an inactive list. Pretend to be a server bot, and say your address is not valid. Hmmmm, could be a neat trick to fool the spammers on Anti-Spam software, I wonder if anyone else thought about it?

Edit: Typo in title.