This works great, but it does not seem to kick in if the user goes to the change email page, and submits an unwanted email domain.
Is there a way to make this work with the change email page, or disable the change email page?
Otherwise a staff person could create a new account with an approved email domain, but using a fake name, then change the email using the change email page to an outside domain, and then we have no idea who they are.