Composite Blocking List
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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. Misconfigured mail servers (for example, servers that send HELO with 'localhost' or a similar incorrect domain.)
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.
[edit] See also
Comparison of DNS blacklists CBL Index - estimate of outgoing spam reputation
