[SOLVED] This User’s On-premises Mailbox Hasn’t Been Migrated To Exchange Online

In a hybrid environment where a user account received the error that the on-site mailbox of this user was not transferred to Exchange Online, I received the odd problem. I was able to resolve the problem and decided to share in this article the methods I followed.

• Go to “Exchange On-Premise“
• Access the “Exchange Management Shell“
• Disable the affected mailbox.

I firmly suggest that remove-mailbox should not be used as it eliminates the AD account connected with a mailbox. I consider using the command Disable.

• Waited for the changes to replicate. After sync, the account had no mailbox in the cloud but they listed in the soft-deleted.
• Enable the on-premise object again using Enable-Mailbox command.

Note: The Enable-mailbox command will not operate if no AD account is active.

• After the sync is completed, initiate migration to Exchange Online from on-premise and assign a respective license.
• The mailbox appears to be ok and no more error (This user’s on-premises mailbox hasn’t been migrated to Exchange Online).

• Now, perform the mailbox restore request to move contents from the soft-deleted mailbox to the active mailbox.
• Finally, add the proxy addresses of soft-deleted mailbox to the active mailbox to make sure all emails receive to the new mailbox.

If the above steps aren’t efficient, follow the instructions in the Microsoft website.

Want to improve your Exchange Online experience for better productivity? Check out the tips and tricks mentioned here