IMAP account lost emails during domain transfer, backup only has "Sync Errors" messages

Question

I was helping someone with a domain transfer, which included their emails moving to a new server.

They were using IMAP to access their emails in Outlook 2013. I instructed them to create a backup of their messages using Export, which they did. Saving all of the messages to a separate data file.

After the transfer completed, I advised them to add that data file to Outlook so they'd have access to their emails. Upon doing this we found that all of the incoming mails in that data file were missing, and instead there was a folder full of thousands of synchronisation errors.

The previous host spent days messing me around to the point that their backup of the mail has apparently expired and been overwritten, so I don't believe it can be recovered from the old mail server. Is there any way of retrieving these mails or repairing the backup he exported to recover those messages?

Answer 1

For the record, Stellar Phoenix PST Repair was able to recover the mails.

I don't have an inexpensive answer which resolves this problem, which is why I won't accept my own answer.