Office 365: removing Litigation Hold mailboxes in an Exchange Hybrid environment

In our hybrid Exchange 2010 / Exchange Online environment, we occasionally need to place an Exchange 2010 mailbox on Litigation Hold. In some cases, that user’s mailbox will need to be removed but the Active Directory account will need to be retained. Exchange 2010 will not allow a mailbox on Litigation Hold to be removed, so our practice has been to simply export the mailbox to PST for retention, manually remove the Litigation Hold, and then remove the mailbox. However, we’ve learned that Exchange Online requires a slight change to that procedure.

Exchange Online was reporting an error regarding a few such users.
Exchange: An unknown error has occurred. Refer to correlation ID:

Referencing this article to help determine the problem, I ran some code against MSOL to look at a more detailed error report.
http://support2.microsoft.com/kb/2741233

$errors = (Get-MsolUser –UserPrincipalName user@domain.edu).Errors
$errors | foreach-object {"`nService: " + $_.ErrorDetail.Name.split("/")[0]; "Error Message: " + $_.ErrorDetail.ObjectErrors.ErrorRecord.ErrorDescription}

The output provided the details need to understand the problem.

Service: exchange
Error Message: Exchange can't disable the mail user "NAMPRXXXXXX.prod.outlook.com/Microsoft Exchange Hosted Organizations/tenant.onmicrosoft.com/user" because it is on litigation hold.

First I tried to simply remove the MsolUser using this command.
Remove-MailUser –Identity name@domain.com –IgnoreLegalHold

However, that returned an error.

The following error occurred during validation in agent 'Windows LiveId Agent': 'Unable to perform the save operation. 'user' is not within a valid server write scope.'

After engaging Microsoft on the problem, we determined there are two options to address the error:

  1. If the MSOL account is not actually required in Azure Active Directory (AAD), we can simply delete it and purge it from the AAD recycle bin. At the next DirSync cycle, a new MsolUser will be created and the error will be resolved. (See the important NOTE below.)
  2. An Exchange Online license could be assigned temporarily to the MsolUser to create a new Exchange Online mailbox. After allowing time for the mailbox to be created plus additional time for a DirSync cycle, remove the Exchange Online license again, and the mailbox will be deleted. This should allow the backend processing to occur and resolve the error.

In most cases, Option 1 is probably most palatable. I issued these two commands, and after the regular DirSync scheduled sync, the error has been resolved. Of course you can add the -Force parameter to quickly execute the commands without having to confirm.

NOTE: If the AAD account is removed, this will also remove the user’s access to other Office 365 data such as OneDrive for Business.

Remove-MsolUser -UserPrincipalName user@domain.edu
Remove-MsolUser -UserPrincipalName user@domain.edu -RemoveFromRecycleBin

In summary, the way to avoid the problem is to remove the Litigation Hold from the Exchange 2010 mailbox, then wait for a DirSync cycle, and then remove the Exchange 2010 mailbox. If both actions are taken quickly together and an error is reported in the Office 365 Admin Center, just purge the AAD account as described above to resolve the error.

About Tommy Doan

BF-ITS(Systems)
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2 Responses to Office 365: removing Litigation Hold mailboxes in an Exchange Hybrid environment

  1. R ARTES says:

    Fantastic hunt, thanks very much Tommy.

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