In computer networking, the Composite Blocking List (CBL) is a DNS-based Blackhole List of suspected E-mail spam senders. The CBL takes its source data from very large spamtraps/mail infrastructures, and only lists IPs exhibiting characteristics such as:
- Open proxies of various sorts (HTTP, socks, AnalogX, wingate etc)
- Worms/viruses that do their own direct mail transmission
- Trojan horse or "stealth" spamware, without doing open proxy tests of any kind.
Entries automatically expire after a period of time. The CBL does not provide public access to gathered evidence. CBL data are used in Spamhaus XBL list.
See also
- Comparison of DNS blacklists
- CBL Index - estimate of outgoing spam reputation
