I saw an unsolved discussion on this elsewhere in the forum and am now having the same issue as the original poster.
We've had a few complaints from people who have unsubscribed, but they're not unsubscribing. Also, I thought that Marketo automatically feeds this back to SalesForce and checks the "do not mail" box.
When we set up filters, we choose the "Don't Mail" and "MKTO Don't Mail" fields to filter those marked in SFDC as not wanting to receive e-mail.
What is happening, why, and how do you fix it? These are standard e-mail blasts, not Operationals.