Unsubscription from bulk mailing sent via search results

When choosing to send a bulk email to contacts via search result, the unsubscribe link unsubscribes the contact from the hidden smart group rather than the base group. As a result, when a second email is sent via search results to the same contact using the same base group, the contact still receives the email.

The proper functionality would be that upon the contact's request to unsubscribe, the contact should be added to the base group with status "removed." Then, future mailings to the same base groups should check if any of the hidden smart group's contacts are already in the base group and are unsubscribed, in which case the email should not be sent to those contacts.

http://forum.civicrm.org/index.php/topic,19962.0.html