Domain Name System-based blocklist
METHOD TO BLOCK HOST FOR E-MAIL SPAM
Realtime Blackhole List; DNSBLs; DNSbl; Rhsbl; RHSbl; URIBL; Dnsbl; RBL (Internet); Real-time Blackhole List; Real-time blackhole list; RHSBL; DNS Blacklist; DNSBL; Domain Name System-based Blackhole List; Domain Name System-based blackhole list; Domain Name System-based block list; Domain Name System-based blocklist
A Domain Name System blocklist, Domain Name System-based blackhole list, Domain Name System blacklist (DNSBL) or real-time blackhole list (RBL) is a service for operation of mail servers to perform a check via a Domain Name System (DNS) query whether a sending host's IP address is blacklisted for email spam. Most mail server software can be configured to check such lists, typically rejecting or flagging messages from such sites.