While Fastmail does a decent job of controlling my Internet junk mail, my shredder is never too far away for the approximately 12,000 credit card offers I receive daily.
A friend tipped me off to a service run by the 3 major credit reporting agencies that allows you to block your information from being shared with banks for marketing purposes. I tried it a month or so back, and I've received dramatically less credit card junk mail.
The number to call is 1-888-567-8688. Experian, one of the participating credit reporting agencies has a page setup that explains the details.