Change alias of Exchange Online mailbox

Our Active Directory is synced to Exchange Online using AD Connect.

After renaming a user I have noticed the Alias field in Exchange Online remains unchanged.

Changing it online fails with this message:

The operation on mailbox "John.Smith" failed because it's out of the current user's write scope. The action 'Set-Mailbox', 'Alias,EmailAddresses', can't be performed on the object 'John Smith' because the object is being synchronized from your on-premises organization. This action should be performed on the object in your on-premises organization.

In AD, there is no where I am able to change it. I have found solutions that state I should change the mailNickName attribute, but this does not appear in the Attribute Editor.

So I followed method 2 of this guide and modified the powershell to be this:

Get-ADUser -Properties * -Filter {name -like "John.Smith"} | set-aduser -replace @{mailnickname="John.Smith"}

Then I ran AD Connect delta sync. But it does nothing, the original Alias is still there.

Solution 1:

Please double check in ADSI. Or did you find proxyaddress, please try to change this, the ProxyAddresses attribute is where the aliases are stored.

Did you ever install Exchange on-premises server in this environment? If not, you could extend Active Directory schema to include Exchange attributes:

http://guides.appriver.com/m/89074/l/698027-extend-active-directory-schema-to-include-exchange-attributes