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
Version 1.0
Blog Post
Shaun Jennings The on-premises mailbox has a different ExchangeGuid than the EXO mailbox. The only place I can see this on-premises mailbox now is with Get-MailboxStatistics, and I'm using the "MailboxGuid" property for the -SourceStoreMailbox parameter on my New-MailboxRestoreRequest command. MailboxGuid from Get-MailboxStatistics is the same as ExchangeGuid from Get-Mailbox (but in this case, I can't do Get-Mailbox since the mailbox has been disabled).
The original mailbox is currently disconnected/soft-deleted. The original user has been Enable-RemoteMailbox'd and Set-RemoteMailbox'd with -ExchangeGuid <Exch.Guid from EXO>
So the answer is yes and no, ha ha. Let me know if I'm missing something though.