Office 365 mailbox not showing in Exchange Hybrid on-premises

An Exchange Hybrid configuration is set up in the organization. When you look in the on-premises Exchange admin center, the Office 365 mailbox is not showing. The mailbox shows only in Office 365. Why is this happening, and what is the solution for Office 365 mailbox not showing in Exchange Hybrid on-premises?

Table of contents

Check mailbox in Exchange Online and Exchange on-premises

There is an Office 365 mailbox when you look in Microsoft 365 Exchange admin center. In our example, the user mailbox is Alison Bell with the email address Alison.Bell@exoip.com.

Office 365 mailbox not showing search mailbox cloud

When you check the on-premises Exchange admin center, the mailbox doesn’t show up. Even a search will not show you the mailbox.

Office 365 mailbox not showing search mailbox on-premises

Let’s try to find the mailbox with PowerShell. Start Exchange Management Shell as administrator. Run Get-RemoteMailbox cmdlet. You will get the output that the object couldn’t be found.

[PS] C:\>Get-RemoteMailbox -Identity "Alison.Bell@exoip.com"
The operation couldn't be performed because object 'Alison.Bell@exoip.com' couldn't be found on
'DC01-2016.exoip.local'.
    + CategoryInfo          : NotSpecified: (:) [Get-RemoteMailbox], ManagementObjectNotFoundException
    + FullyQualifiedErrorId : [Server=EX01-2016,RequestId=ac7b9c98-6913-4c83-a35c-4351e7308fe4,TimeStamp=6/21/2021 9:2
   5:50 PM] [FailureCategory=Cmdlet-ManagementObjectNotFoundException] 1B6A5890,Microsoft.Exchange.Management.Recipie
  ntTasks.GetRemoteMailbox
    + PSComputerName        : ex01-2016.exoip.local

Why is this happening, and what is the solution for Office 365 mailbox not showing in Exchange Hybrid on-premises?

Why Office 365 mailbox is not showing in Exchange admin center

The Office 365 mailbox does not show up in Exchange on-premises because:

  • You create an on-premises Active Directory user account and assign a license to the mailbox without the Enable-RemoteMailbox cmdlet.
  • You create an on-premises Active Directory user account and create the mailbox in Office 365 (cloud) without the Enable-RemoteMailbox cmdlet.

Let’s look at how to fix the Office 365 mailbox not showing in Exchange on-premises.

Solution for Office 365 mailbox not showing in Exchange admin center

Run Exchange Management Shell as administrator and run the following three cmdlets.

Step 1. Run Enable-MailUser cmdlet to mail-enable the user that isn’t already mail-enabled (Exchange on-premises).

[PS] C:\>Enable-MailUser -Identity "Alison.Bell@exoip.com" -ExternalEmailAddress "Alison.Bell@exoip365.mail.onmicrosoft.com"

Name            RecipientType
----            -------------
Alison Bell     MailUser

Do you get an error after running the above cmdlet? Read the article ExchangeGuid is mandatory on UserMailbox.

Step 2. Run Enable-RemoteMailbox cmdlet to link the cloud mailbox in the cloud-based service for the existing user in the on-premises Active Directory (Exchange on-premises).

[PS] C:\>Enable-RemoteMailbox "Alison.Bell@exoip.com"

Name            RecipientTypeDetails     RemoteRecipientType
----            --------------------     -------------------
Alison Bell     RemoteUserMailbox        ProvisionMailbox

Step 3. Connect to Exchange Online PowerShell and run Get-Mailbox cmdlet to get the ExchangeGuid property and copy the value (Exchange Online).

PS C:\> Connect-ExchangeOnline

PS C:\> Get-Mailbox "Alison.Bell@exoip.com" | ft Identity,ExchangeGuid

Identity    ExchangeGuid                        
--------    ------------                        
Alison Bell 8a3a004c-131a-4914-8951-cb41f50fe024

Step 4. Run Set-RemoteMailbox cmdlet to set the ExchangeGuid property on the AD on-premises user object (Exchange on-premises).

[PS] C:\>Set-RemoteMailbox "Alison.Bell@exoip.com" -ExchangeGuid "8a3a004c-131a-4914-8951-cb41f50fe024"

Step 5. Run Get-RemoteMailbox cmdlet and verify that the ExchangeGuid is set on the on-premises AD user object (Exchange on-premises).

[PS] C:\>Get-RemoteMailbox "Alison.Bell@exoip.com" | fl Identity,ExchangeGuid


Identity     : exoip.local/Company/Users/HR/Alison Bell
ExchangeGuid : 8a3a004c-131a-4914-8951-cb41f50fe024

Step 6. Force sync Azure AD Connect with PowerShell.

PS C:\> Start-ADSyncSyncCycle -PolicyType Delta

Verify Office 365 mailbox showing in Exchange on-premises

Check in the on-premises Exchange admin center that the Office 365 mailbox shows up.

Office 365 mailbox not showing verify mailbox

Another check, but this time in Exchange Management Shell. Run Get-RemoteMailbox cmdlet.

[PS] C:\>Get-RemoteMailbox -Identity "Alison.Bell@exoip.com"

Name            RecipientTypeDetails     RemoteRecipientType
----            --------------------     -------------------
Alison Bell     RemoteUserMailbox        ProvisionMailbox

Everything looks great!

Read more: Create Office 365 mailbox in Exchange Hybrid »

Conclusion

You learned why the Office 365 mailbox is not showing in Exchange Hybrid on-premises. The solution to this problem is to run both the Enable-MailUser and Enable-RemoteMailbox cmdlets against the on-premises Active Directory user. After that, the Office 365 mailbox shows up in the on-premises Exchange Server.

Did you enjoy this article? You may also like the course Exchange Hybrid. Don’t forget to follow us and share this article.

ALI TAJRAN

ALI TAJRAN

ALI TAJRAN is a passionate IT Architect, IT Consultant, and Microsoft Certified Trainer. He started Information Technology at a very young age, and his goal is to teach and inspire others. Read more »

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This Post Has 33 Comments

  1. Hi Ali,
    Thank you very much for all the work you do. I have a question regarding this. In my situation i have fixed it for one user. I want to as if i have 100 for exaple. Is there a way to do it for multiple users. Is re-runnung the Hybrid configuration wizzrds going to fix the missing attributes ?
    Thank you.

    Reply

  2. My problem is that we are in hybrid. Account originally created in on-premise then migrated to O365. Sync via Azure AD Sync. After we took this account of sync it turns out as deleted. Then we resync it again, restore it from delete, asign a licence but the mailbox is missing. It is not shown in Exchange Online. Non of this above worked. It is not for our problem. Ali please, can you help?

    Reply

  5. Thank you very much, Ali – I come back to your articles time and again, and I appreciate the information you provide.

    Can you please tell me if there is any impact to the existing mailbox when this is done – e.g. will they still be able to access their mailbox while this work is being done?

    Thank you

    Reply

  6. Thank you, this worked for us.

    Is there a way to have this happen automatically when we create a new mailbox in O365? Or do we have to do this for ever new user if we synch the AD account and then create the mailbox by assigning a license on O365?

    Seems to be a lot of work to have a local mail enabled box show up, and before discovering this issue, I assumed all of this would happen automatically since we are still in hybrid mode.

    Reply

      1. Thank you. I just realized that when we first migrated over this past summer, we were using the on prem server to create O365 mailboxes, and those all work fine, but at some point, we just started creating O365 mailboxes by assigning Exchange Online licenses. We never realized that meant the user didn’t have a mail object created in the on prem server.

        Thank you for the reply and this article as it has been very helpful to understand this.

        Reply

  9. Thank you Ali. I keep coming back to this article whenever I need to. Quick question, was Step 3 (setting GUID) added later to this article? I don’t remember seeing this step before. What does setting the GUID do and why do I need it?

    Reply

  12. Does anyone have a script to map all Exchange Online mailbox GUID and enable on premise Active Directory accounts as RemoteMailbox and apply Exchange GUID? Thanks!

    Reply

  13. Great article Ali. In the event mailbox was created directly in EXO/O365 without an AD object, any good solution for this other than delete EXO object and re-create EX object correctly?

    Reply

  15. I should add to my last comment:
    Enable-Mailuser says it is already of type MailUser
    Enable-RemoteMailbox says “Specified argument was out of the range of valid values”
    I can get the Guid just fine
    set-remotemailbox says the mailbox cannot be found on the domain controller

    But the user is in AD and the mailbox is in Office 365, but not in on-prem Exchange.

    Reply

  16. So, in my case, when I use the enable-mailuser command, it tells me the account is of type MailUser already, but it still does not show up in on-Prem Exchange.

    Reply

  19. This works great for regular mailboxes, thank you!
    How would we update Distribution group, Shared Mailbox and Room Mailbox attributes created before we had a Exchange 2016 Management Server to have them show in Exchange 2016 Admin Center?

    Reply

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