I had the unfortunate opportunity yesterday to come in to work only to find that all of our Public Folders had been deleted from the our Exchange 5.5 site. It seems the administrator from another site had finished migrating from Exchange 5.5 to Exchange 2003. He decided he didn't want “everyone else’s” Public Folders showing up in his tree, and since he couldn't see the content of the folders, figured they were local copies only. Delete. Whoops. This had happened once before, when our parent company upgraded to Exchange 2000. Since that incident, we marked all Public Folders here to Limit Administrative Access to Home Site. We assumed this would cover deletions as well as re-homing a folder or assigning\removing replicas.
We had some issues recently with our Public Folder bricked backups. We make brick backups of the Public Folders as it allows for a much more rapid restore in an Exchange 5.5 environment. We had a complete set of the Public Folders also replicated to our Exchange 2003 environment. My initial thought was that it wouldn't be too much trouble to replicate them back to another Exchange 5.5 server. After about three hours, we cried uncle and called MS PSS. After about another 2 hours with MS PSS and no traction, I finally remembered, we have Public Folder Deleted Item Retention turned on. Viola! Restore operation began. Create an Outlook profile with the Exchange Administrator account (owner of all Public Folders for backup purposes) and away we went. Of course, there are a few folders where the owners thought it was wise to remove the Exchange Administrator from the permissions list for “confidentiality sake.” So they will take a few more steps to restore.
If you have the disk space, look to deleted item retention as a disaster recovery tool.