DNS blocklists

The SpamCop Blocking List (SCBL) lists IP addresses which have transmitted reported email to SpamCop users. The SCBL is a fast and automatic list of sites sending reported mail, fueled by a number of sources, including automated reports and SpamCop user submissions. The SCBL is time-based, resulting in quick and automatic delisting of these sites when reports stop.

The SBL is a realtime database of IP addresses of verified spam sources (including spammers, spam gangs and spam support services), maintained by the Spamhaus Project team and supplied as a free service to help email administrators better manage incoming email streams. The SBL is queriable in realtime by mail systems thoughout the Internet, allowing email administrators to identify or block incoming connections from IP addresses involved in the sending of Unsolicited Bulk Email.

The Spamhaus Exploits Block List (XBL) is a realtime database of IP addresses of illegal 3rd party exploits, including open proxies, worms/viruses with built-in spam engines, and other types of trojan-horse exploits.

Blackholes.us publishes the IP range of many countries and ISP in a format usable for blocking with your email server. If, for example, you receive a lot of spam from China but you do not communicate with anyone in that country, blocking them would be beneficial.