def get(mail_host, default=None):
    """Return the named domain.

        :param mail_host: The email host name of the domain to remove.
        :type mail_host: string
        :param default: What to return if the named domain does not exist.
        :type default: object
        :return: The domain object or None if the named domain does not exist.
        :rtype: `IDomain`
        """
