def add(alias):
    """Add the given address as an acceptable aliases for posting.

        :param alias: The email address to accept as a recipient for implicit
            destination posting purposes.  The alias is coerced to lower
            case.  If `alias` begins with a '^' character, it is interpreted
            as a regular expression, otherwise it must be an email address.
        :type alias: string
        :raises ValueError: when the alias neither starts with '^' nor has an
            '@' sign in it.
        """
