I'm using the ExMerge utility to migrate mailboxes to a new server. The mailboxes all backup fine with no errors, but when I tried the restore on the new server, 11 of the mailboxes were aborted. When I examined the logfile I discovered that these 11 users were backed up with strange PST file names.
Rather than a file named USERNAME.PST these few had extra numbers in the name so they looked like USERNAME22375602.PST - all of the accounts in question have 8 numbers added before the .PST.
When the restore runs, it polls Active Directory to get the usernames and then adds the .PST on, so the restore looks explicitly for USERNAME.PST. When it doesn't find that match it aborts that particular mailbox. I've been told that an acceptable workaround is to just rename the .PST files to remove the extra numbers, but I have not been able to find out what wold cause these mailboxes to be named this way in the first place.
Some possible suggestions I've heard are that the mailboxes were changed somehow since they were created, either a username change or they were detached fro the mail store. I'm hoping that someone who understands this process better than me can shed some light on these file names and what is significant about the 8 extra numbers.