Enable-RemoteMailbox ExchangeGuid is mandatory on UserMailbox

After you run the Enable-RemoteMailbox cmdlet to create an Exchange Online mailbox for an existing on-premises user, it fails. The errors show that ExchangeGuid is mandatory on UserMailbox and Database is mandatory on UserMailbox. What’s happening, and what is the solution to these errors?

The organization got a hybrid environment, and the mailboxes are in Exchange Online (Office 365). After you create the users in Active Directory on-premises, Azure AD Connect will sync the AD objects to Azure Active Directory. The last step is to create an Exchange Online mailbox for the users with the Enable-RemoteMailbox PowerShell cmdlet.

ExchangeGuid is mandatory on UserMailbox

You have a hybrid environment that syncs the on-premises Active Directory to Azure Active Directory. After you create a new AD user on-premises, you want to create a new Exchange Online mailbox (Office 365).

In this example, the user Ali Tajran is already created in AD on-premises and synced to Azure AD. Make sure that the AD object appears in Azure AD or Microsoft 365 admin center.

Note: Use the Enable-RemoteMailbox cmdlet to create a mailbox in the cloud-based service for an existing user in the on-premises Active Directory. This cmdlet is available only in on-premises Exchange.

Run Exchange Management Shell as administrator. Use the Enable-RemoteMailbox cmdlet to enable a remote mailbox.

[PS] C:\>Enable-RemoteMailbox -Identity "Ali Tajran" -RemoteRoutingAddress "Ali.Tajran@exoip.mail.onmicrosoft.com"

After running the command, the output gives us the following errors:

• ExchangeGuid is mandatory on UserMailbox.
• Database is mandatory on UserMailbox.

ExchangeGuid is mandatory on UserMailbox.
    + CategoryInfo          : NotSpecified: (exoip.local/Company/I...Ali Tajran:ADObjectId) [Enable-RemoteMailbox], DataValidationException
    + FullyQualifiedErrorId : [Server=EX01-2016,RequestId=0a83a0bb-6893-4768-8be7-d23f6f65413f,TimeStamp=14-1-2021 18:43:16] [FailureCategory=
   Cmdlet-DataValidationException] 228B08D6,Microsoft.Exchange.Management.RecipientTasks.EnableRemoteMailbox
    + PSComputerName        : ex01-2016.exoip.local

Database is mandatory on UserMailbox.
    + CategoryInfo          : NotSpecified: (exoip.local/Company/I...Ali Tajran:ADObjectId) [Enable-RemoteMailbox], DataValidationException
    + FullyQualifiedErrorId : [Server=EX01-2016,RequestId=0a83a0bb-6893-4768-8be7-d23f6f65413f,TimeStamp=14-1-2021 18:43:16] [FailureCategory=
   Cmdlet-DataValidationException] 27A58729,Microsoft.Exchange.Management.RecipientTasks.EnableRemoteMailbox
    + PSComputerName        : ex01-2016.exoip.local

Why do we get this error, and what is the solution for ExchangeGuid is mandatory on UserMailbox and Database is mandatory on UserMailbox?

Solution for ExchangeGuid is mandatory on UserMailbox

Start Active Directory Users and Computers (ADUC) on the on-premises server. Click in the menu bar on View and enable Advanced Features.

Find the user object and double-click on it to open the properties. Click the tab Attribute Editor. Find the attribute msExchHomeServerName and click Edit.

This is how the value looks.

Click on Clear to clear the value for attribute msExchHomeServerName. Click OK.

The value changed to <not set>. Click OK.

It’s important to force a sync to Azure AD before you run the Enable-RemoteMailbox cmdlet.

PS C:\> Start-ADSyncSyncCycle -PolicyType Delta

Now rerun the Enable-RemoteMailbox command.

[PS] C:\>Enable-RemoteMailbox -Identity "Ali Tajran" -RemoteRoutingAddress "Ali.Tajran@exoip.mail.onmicrosoft.com"

Name                     RecipientTypeDetails               RemoteRecipientType   
----                     --------------------               -------------------
Ali Tajran               RemoteUserMailbox                  ProvisionMailbox

The mailbox is created in Office 365.

Bulk clear attribute msExchHomeServerName value

Editing the attribute one by one by one is time-consuming. What if you want to clear the msExchHomeServerName attribute value from all the users?

Use the Get-ADUser cmdlet to find all user objects that don’t have the value cleared.

[PS] C:\>Get-ADUser -Filter * -Properties msExchHomeServerName | Where-Object {($_.msExchHomeServerName -ne $null) -and $_.Name -notlike "HealthMailbox*" -and $_.Name -notlike "SystemMailbox*" -and $_.Name -notlike "FederatedEmail*" -and $_.Name -notlike "Migration*"} | Select-Object SamAccountName,msExchHomeServerName

SamAccountName  msExchHomeServerName                                                                                
--------------  --------------------                                                                                
Administrator   /o=EXOIP/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Configuration/cn=Servers/cn=EX02-2016
Max.Fraser      /o=EXOIP/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Configuration/cn=Servers/cn=EX02-2016
Piers.Bower     /o=EXOIP/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Configuration/cn=Servers/cn=EX02-2016
Kylie.Davidson  /o=EXOIP/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Configuration/cn=Servers/cn=EX02-2016
Richard.Grant   /o=EXOIP/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Configuration/cn=Servers/cn=EX02-2016
Boris.Campbell  /o=EXOIP/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Configuration/cn=Servers/cn=EX02-2016

Export the results to a CSV file in the C:\temp folder. Create a temp folder if you don’t have one.

[PS] C:\>Get-ADUser -Filter * -Properties msExchHomeServerName | Where-Object {($_.msExchHomeServerName -ne $null) -and $_.Name -notlike "HealthMailbox*" -and $_.Name -notlike "SystemMailbox*" -and $_.Name -notlike "FederatedEmail*" -and $_.Name -notlike "Migration*"} | Select-Object SamAccountName,msExchHomeServerName | Export-Csv "C:\temp\users.csv" -Encoding UTF8 -NoTypeInformation

Open the CSV file with Microsoft Excel or another application of your choice. In this example, we used Notepad.

Clear the attribute msExchHomeServerName value for the AD users. Copy the script below and paste it in PowerShell ISE and run the script.

$Users = Import-Csv "C:\temp\users.csv"
Foreach ($User in $Users) {
    Get-ADUser $User.SamAccountName | Set-ADUser -Clear msExchHomeServerName
}

Don’t forget to force a sync to azure AD before you run the Enable-RemoteMailbox cmdlet.

Did this help you to fix the ExchangeGuid is mandatory on UserMailbox and Database is mandatory on UserMailbox errors?

Articles that you may be interested in:

• Create Office 365 mailbox in Exchange Hybrid
• Bulk create Office 365 mailboxes in Exchange Hybrid

Conclusion

You learned why you receive the error ExchangeGuid is mandatory on UserMailbox and that Database is mandatory on UserMailbox after running the Enable-RemoteMailbox cmdlet.

The solution to this problem is to clear the attribute value msExchHomeServerName on the on-premises AD object. After that, force a sync to Azure AD and run the Enable-RemoteMailbox command. No more errors and the mailbox is created in Office 365.

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