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 Thanks for the response. Regarding where a warning might be placed - I'm not sure where would be best since it's a topic spanning AAD licensing, AAD Connect syncing, and everything around and in between. Because of that (the difficulty of documenting this where the warning will have preventative value), I feel like it's actually something that could merit a feature addition, allowing hybrid Exchange customers to somehow turn off auto-provisioning of mailboxes until the on-premises steps are completed (e.g. either New-RemoteMailbox or Enable-RemoteMailbox, and sync of ExchangeGuid). I can feel this one going the UserVoice path, as much as I fear that is a graveyard for unpopular-but-great ideas.
I will open a case for the failing New-MailboxRestoreRequest and see what can be found out there. In case the error is common or expected under certain conditions, a warning note block could be added to the linked docs page from this blog post. I'll report back once I've gone through support.