Hi CM-guys, I read somewhere that it's possible to replace the "Mark as spam" buttons in Gmail and Hotmail by "Unsubscribe from this sender" (or something like that), by adding a special kind of header to an email. Have you heard about that one? Maybe you even know what that header should be?
Both require the List-Unsubscribe tag in the headers, which is present in all email sent from us. Hotmail only shows it if the sender is in the recipients safe sender list, another reason to encourage your subscribers to add you to their address book, safe sender lists, etc.