Our Exchange 2003 server had a catastrophic failure which corrupted the contents of the Exchange databases. Soft recovery failed due to excessive corruption. At 72GB, a hard recovery was not really an option due to disk space and the time it would have taken to do the eseutil /p and eseutil /d. There were a ton of log files missing too so data loss would probably have been quite high. We got the client up and running with a blank mailbox store, restored the most recent backup using NTBackup into a Recovery Storage Group and recovered individual mailboxes into the production database. This worked just fine.
How do I restore Public Folders from the NTBackup backup into a production environment, without affecting the Mailbox Store in anyway, which is working just fine now.
Is it as simple as setting their current production public folder store (empty) to be overwritable and selecting the public folder from the backup selection list in NTBackup? As they are up and running with their mailbox store, I wouldn't want to do anything that might break it again.
Sounds like you had a "fun" time.
You've got it right in your last paragraph. Mark the public folder store as being overwritable and restore into it. It won't interrupt access to the mailbox store (though, at 3GB maximum address space, the server may be a little bit sluggish during the restore since you'll be thrashing the I/O a bit more than usual).