I have a domain setup and configured on outlook.com "leyland leisure sales dot co dot uk" for which i have a single account with multiple aliases configured.  However, i have one alias "michael@leyland...." which will not provision.  Every time, i receive an error "The call failed with outcome: SoapException Error 9003: Passport error."

I have verified that this account does not exist anywhere else, it isn't an un-managed account, and it isn't already added as an alias.  I'm assuming that it did previously exist, and this is what is preventing me from proceeding.  Is anyone able to assist in the removal of this hidden attribute anywhere?