The Curious MC146221 Update
Microsoft published update MC146221 in the Office 365 Message Center on August 8, 2018. The text is a masterpiece of obfuscation. It announces a new feature, but really what is happening here is that Microsoft has fixed a bug in the Set-UnifiedGroup cmdlet so that you can remove proxy email addresses from an Office 365 Group. Although the notice says that Microsoft is releasing a new cmdlet, it’s just a fix for a cmdlet that’s been around since the introduction of Office 365 Groups in November 2014.
Reclaiming an Email Address
When Microsoft says that “it was not possible to reclaim email addresses of Groups,” it means that the Set-UnifiedGroup cmdlet didn’t work when you tried to remove a proxy address from the list held in a group’s EmailAddresses attribute. The bug has now been fixed.
In the following example, we examine the set of addresses for a group and then remove one. When we check the EmailAddresses attribute again, the address we removed is gone, which is what we want. In Microsoft terms, the address is reclaimed because it can now be assigned to another mail-enabled object.
Get-UnifiedGroup -Identity BankingTeam | select -ExpandProperty emailaddresses
SMTP:BankTeam@office365itpros.com
smtp:BankingTeam@Office365itpros.com
smtp:BankingGroup@Office365itpros.com
smtp:CorporateBanking@office365itpros.com
Set-UnifiedGroup -Identity BankingTeam -EmailAddresses @{Remove="BankingTeam@Office365itpros.com"}
Get-UnifiedGroup -Identity BankingTeam | select -ExpandProperty emailaddresses
SMTP:BankTeam@office365itpros.com
smtp:BankingGroup@Office365itpros.com
smtp:CorporateBanking@office365itpros.com
You can’t remove the primary SMTP address of a group without reassigning primary status to another address first.
Be Careful
Before you rush out to reclaim addresses, remember why proxy addresses exist. If you remove an address from Object A and assign it to Object B, any email sent to that address will be delivered to Object B. This might not be what you want to happen. Keeping a set of proxy addresses for an object allows that object to continue receiving email for those addresses after its primary SMTP address changes. This might not be so important for an Office 365 Group, but it is for user and shared mailboxes.
For more information about using PowerShell with Office 365 Groups, see Chapter 14 in Office 365 for IT Pros. Management of Office 365 Groups is described in Chapter 12.