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Fixing Office 365 Mailbox Does Not Exist: Step-by-Step Guide

Today, I’ve got a solution for you on tackling the pesky Office 365 mailbox does not exist” issue. I recently faced a bit of a challenge when a user was linked to a remote user mailbox on-premises, but there was no corresponding mailbox provisioned in Microsoft 365, despite having an Exchange Online license.

Let’s dive into the strategies to fix this hiccup.

First off, if you’re in a hybrid environment with Microsoft Entra Connect for syncing objects, the Exchange GUID in on-premises needs an update.

Here’s the friendly step-by-step guide:

  • Access your Exchange server.
  • Launch the “Exchange Management Shell.”
  • Give that Exchange GUID a makeover by setting it to null for the affected mailbox.

    Set-RemoteMailbox Display Name” -ExchangeGuid 00000000-0000-0000-0000-000000000000

If you’re curious about the Remote Mailbox, hop on over to the Microsoft website for all the deets.

Office 365 mailbox does not exist
  • Now, let’s make sure your ExchangeGUID info is spot-on in your on-premises setup. Just fire up this command:

    Get-RemoteMailbox “Display Name” | fl ExchangeGUID
user has no mailbox and no license assigned error
  • Wait for the changes to reflect in cloud. The object in Microsoft 365 should show the same ExchangeGUID that we set in on-premises.
  • Don’t forget to be patient—wait for those changes to show up in the cloud. Your Microsoft 365 object should sport the same ExchangeGUID you’ve set on-premises. Need help connecting to Exchange Online PowerShell? Check out this handy website.
non existent mailbox exception
  • Voila! Once those changes sync up with Microsoft 365, it’s time to do a little dance. Start by removing the Exchange online license from the affected account, wait around 15 minutes, then pop that license back on. Quick check with this command:

Get-Mailbox “Display Name” | fl ExchangeGUID,Recipienttype*

mailbox does not exist

And there you have it! Your object is now strutting its stuff as a user mailbox in the cloud. Say goodbye to the office 365 mailbox does not exist hiccup. If you’re dealing with a user has no mailbox and no license assigned error or facing an error non existent mailbox exception, fret not! Our tips and tricks are designed to help you navigate and troubleshoot these issues seamlessly.

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

Now, over to you! Did I cover everything, or is there something on your mind? Drop a comment below.

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  2. Cicindela

    Hi, thank you this work well, i got MailboxOnline but ExchangeGUID is different between remotemailbox ( 00000000-0000-0000-0000-000000000000) and onlineMailbox ( New ExchangeGUID). Is it a problem ?

    • techieberry

      Tested the behavior in a hybrid environment and the mailbox is not being deleted. It is also showing a mailbox in Exchange online.

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