Why not just bind the sso Mail to an local Account, then it doesn't matter what identity Provider gets used by the customer. In addition, add a check that preve

Why not just bind the sso Mail to an local Account, then it doesn't matter what identity Provider gets used by the customer. In addition, add a check that prevents Account creation of ...@privacyrelay...if you have a problem with it or nag the user to provide a real mail for this account if you detect this type of mail. This way you would have a user friendly implementation without giving up on sso.