In support, we hear from people in this “duplicate mailbox” situation relatively often. When this happens, our customers ask us for the best way to recover. In my experience, there are typically two ...
Published Sep 11, 2019
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Blog Post
bwinzenz
Microsoft
MicrosoftJeremyTBradshaw Shaun Jennings Sorry guys - I just got back from vacation and just now catching up. First things first...
Exchange guid does not have to match. Kind of the whole point of this remote restore concept is you are restoring from the on-prem disconnected mailbox into a *different* mailbox in EXO. I've tested it many times (and worked with a customer just today to do one!)
Secondly - remember that this is a "restore" request, not a "migration". If the restore request is "copying" items, I'm really not concerned about the errors referencing cannot find Exchange guid, or even if the restore request fails (at the very end). In the example provided, you can see that 799 items were successfully copied. That is really all that is important here. Yes that means there is likely room for improvement, and it is possible there could have been a code change on the EXO side that is causing the failure, but focus on the item copy. As long as the messages show up in the target (EXO) mailbox, everything worked.
Copy progress: 799/799 messages
Secondly - regarding your scenario of premature licensing, the ONLY time there should be an issue with licensing creating a mailbox in EXO is if the user is licensed BEFORE the Exchange guid is synchronized. If a company is going to set up AAD Connect and synchronize users, they should be syncing Exchange attributes. It isn't that hard. It is just a check box in the AAD Connect wizard. They don't have to configure full Hybrid using the Hybrid Configuration Wizard. Just sync Exchange attributes.
Hope this helps - happy to have a further discussion offline if it makes more sense. Drop your email address here and I'll reach out.