[SOLVED] Office 365 Mailbox Does Not Exist

Today I’m going to show you how to solve office 365 mailbox does not exist issue.

I had a painful day where a user had a mailbox (remote user mailbox) in on-premise but the Microsoft 365 mailbox was not available. The strategies in this post help you to solve this issue.

Let’s jump right in.

In this case, the Exchange GUID needs to be updated in on-premise because of a hybrid environment and using the AAD connect to sync objects.

To update the attribute, follow the below steps.

• Go to “Exchange on-premise PowerShell“
• Update the Exchange GUID to null on the affected mailbox
  For example, set-remotemailbox test2222 -ExchangeGuid 00000000-0000-0000-0000-000000000000

For more information about Remote Mailbox, Visit the Microsoft website.

• Make sure the ExchangeGUID reflects correctly in on-premise. If no for some reason, followed the steps mentioned in this article.

• Wait until the changes synced to cloud. The object in Microsoft 365 should reflect the changes made in on-premise.

• As you can see, the changes synced to Microsoft 365. The next step is to remove the Exchange online license and wait for 15 minutes and then re-add the license and check the status.

Woohoo!!. The object in cloud shows as a user mailbox. The office 365 mailbox does not exist issue is solved.

Also Read: How To Solve Shared Mailbox Showing As Mail User

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

Now I’d like to hear from you:

Did I Miss Anything? Or maybe you have a question about something that I covered.

Either way, I’d like to hear from you. So go ahead and leave a comment below.