Says Mailboxes are in use even though no campaigns are running

I have run many campaigns with no problem. Now, when creating a new campaign it says all my mailboxes are currently in use, and that i need to add more mailboxes. However i should have a bunch of email accounts available for use in a new campaign as i added 12 accounts and none are in use. it says they are in use.. What can i do to fix this? the last campaigns they were used in are finished. It doesnt make any sense. I also cannot remove and re add them as it says they are in use in the mailboxes tab also..