We accidently applied a Managed Folder Mailbox Policy to the entire mailbox population that marked messages older than 90 days as expired. We have fixed the issue and applied the right policy to the mailboxes, however, all messages still have the expired header and the cross-line on the subject. So far the only way we found to unmark messages as expired is manually by un-checking the expire option from the messages header. Our question is, Is there a way to reverse the mentioned policy and un-mark all expired messages?

There is no option to reverse it. We dont have to option to create new mailbox policy to reverse the setting. :(

Hi Alaa, Maybe you need to do that manually, I also tested in my lab, when I change the Managed Folder Mailbox Policy, the expired messages are still marked as expired I will continue to work on this issue, if I get any other workaround, I will update the post. Thanks, Evan Liu TechNet Subscriber Support in forum If you have any feedback on our support, please contact tngfb@microsoft.com