RBL

RBL is an abbreviation for "Real-time Blackhole List". As mentioned below, "RBL" was the name of the first system to use this technology. However, "RBL" is a trademark for the proprietary MAPS DNSBL. Some pieces of mail software have configuration parameters that use "RBLs" or "RBL domains" when any DNSBLs can be used, not just the MAPS RBL.