Composite Blocking List
From Seo Wiki - Search Engine Optimization and Programming Languages
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.