How to remove synced mail users

Question

Hi everyone,

We have an evironment with about 6500 mailboxes federated with EOP and a few mailboxes in Office 365.

Recently I started cleaning out all errors that showed in IDFix, which is completely clean now. Afterwards  I replaced DirSync with AAD Connect.

Some users cannot be exported to Azure AD as the Mail or ProxyAddress attribute is already in use. When we chacked, in Office 365 there are mailusers that needed to be gone a long time ago. While cleaning out AAD Connect, we had the same issues with existing users in Office 365 that could be removed using remove-msoluser, but I cannot get rid of the MailUsers as Remove-MailUser...

When I try to remove the mailboxes in the ECP, I get the following error:

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

Of course we double-checked. They do not exist in Exchange On-Premises, nor in Active Directory.

Please help me out getting rid of these mail users.

Kind regards,

Christof

Answer 1

Hi Christof,

Have you tried to remove the user account via Office 365 Admin center or PowerShell?

If there is any error message when removing, please let me know.

Thanks,

Franky

Answer 2

Remove the associated user account via the O365 Admin portal. Or use PowerShell and the Remove-MsolUser cmdlet. Don't forget to also remove them from the Recycle bin.