Question
When deleting a user who is leaving the company from Access Control, I plan to convert the user account to a shared mailbox in Microsoft 365 in order to retain the mailbox data, even after revoking the license. Are there any considerations regarding user synchronization with Access Control?
[Microsoft] Convert a user mailbox to a shared mailbox (external site)
Answer
If you are going to delete a user who will be converted to a shared mailbox from the user list in Access Control, you must first change the UPN domain of the target user account in Microsoft 365 to a non-synchronized domain, such as the onmicrosoft.com domain.
If you delete a user in Access Control while the user in Microsoft 365 is still using a synchronized domain, the user who was converted to a shared mailbox will be deleted during user synchronization and become a "deleted user."
If a user is deleted, please restore the user using the steps below, and then change the domain again.
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