Is it possible to subscribe again with the same email address? I've tried manually inserting it back into the mailing list and it won't take. The (former) subscriber is on AOL.
when a subscriber marks an email as spam, it's added to the suppression list. To be able to resubscribe it, you have to remove it from the suppression list first.
Click "Manage Subscribers"
Click "Suppression list"
Search for the address in the search box at the right
Check the check box for that subscriber
Click the "Remove selected" button
After that, you should be able to resubscribe the subscriber.
Once someone has marked as spam or unsubscribed they'll also be in an unsubscribed state in your list, so instead of manually adding them to your list you'll need to move them from that unsubscribed state back to active. There are some instructions here that explain how. Alternately, if you have a subscriber form they can just resubscribe using that.
That easy, huh. Thanks so much!