Change user's login email
        :param user: AuthUser
        :param email:
        :return:

def change_email(self, email):
        """
        Change user's login email
        :param user: AuthUser
        :param email:
        :return:
        """

        def cb():
            if not utils.is_email_valid(email):
                raise exceptions.AuthError("Email address invalid")
            self.user.change_email(email)
            return email

        return signals.user_update(self, ACTIONS["EMAIL"], cb,
                                   {"email": self.email})