Get the RelayIpList list for the SMTP virtual server.

    :param str server: The SMTP server name.

    :return: A list of the relay IPs.
    :rtype: list

    .. note::

        A return value of None corresponds to the restrictive 'Only the list below' GUI parameter
        with an empty access list, and setting an empty list/tuple corresponds to the more
        permissive 'All except the list below' GUI parameter.

    CLI Example:

    .. code-block:: bash

        salt '*' win_smtp_server.get_relay_ip_list

def get_relay_ip_list(server=_DEFAULT_SERVER):
    '''
    Get the RelayIpList list for the SMTP virtual server.

    :param str server: The SMTP server name.

    :return: A list of the relay IPs.
    :rtype: list

    .. note::

        A return value of None corresponds to the restrictive 'Only the list below' GUI parameter
        with an empty access list, and setting an empty list/tuple corresponds to the more
        permissive 'All except the list below' GUI parameter.

    CLI Example:

    .. code-block:: bash

        salt '*' win_smtp_server.get_relay_ip_list
    '''
    ret = list()
    setting = 'RelayIpList'

    lines = _get_wmi_setting('IIsSmtpServerSetting', setting, server)

    if not lines:
        _LOG.debug('%s is empty: %s', setting, lines)
        if lines is None:
            lines = [None]
        return list(lines)

    # WMI returns the addresses as a tuple of individual octets, so we
    # need to group them and reassemble them into IP addresses.
    i = 0
    while i < len(lines):
        octets = [six.text_type(x) for x in lines[i: i + 4]]
        address = '.'.join(octets)
        ret.append(address)
        i += 4
    return ret