And don't just go for the one list that sent you. Let them know that you want off of ALL of their lists. Inform them that they'll be hearing from you again if they refuse to remove you.
Persistence is golden.
In fact, I've even gotten companies to seriously re-evaluate the way they work and the clients they hold. If you prefer, you'll never have to see spam at your REAL account. Or you can check it every month or so. It can't hurt to protect yourself.