You can add additional RBL services in the Real-time Black List Services section.To add an RBL service, click Add. In the Add RBL Domain window, you specify the RBL domain to be queried, enable it for use, and specify its expected response codes. Most RBL services list the responses they provide on their Web site, although selecting Block All Responses is generally acceptable.Statistics are maintained for each RBL Service in the RBL Service table, and can be viewed with a mouseover of the (statistics) icon to the right on the service entry.