DNS blacklists

Anti-spam technique: DNS blacklists
Date of first use: about 1997
Effectiveness: High to Low
Popularity: High
Difficulty of implementation: Medium
Where implemented: MTA
Harm: Low to High

DNS blacklists publish lists of IP addresses that share an undesirable characteristic. The characteristic is most often a history of sending spam, but lists also exist that include IP addresses whose owners assert they shouldn't be sending mail, addresses in a geographic region, hosts that are believed not to conform to relevant RFCs, and a wide range of other criteria.

The technical operation of DNSBLs is decribed at Description_of_DNSBLs.