A better solution is one button which both attempts to automatically unsubscribe, and blocks further emails if the list does not respect the user's choice.
Why should I have to do extra work just because MTV is hostile to users? Or because Hallmark's database takes 10 days to update, gamespot's unsubscribe servers are permanently broken, or because some crappy website demands your login info?
http://imgur.com/mzqKk http://imgur.com/Yn5eD http://i.imgur.com/yoky5.jpg