The Composite Blocking List (CBL) is a spam blacklist. It lists IP addresses exhibiting characteristics which are specific to open proxies of various sorts (HTTP, socks, AnalogX, wingate, Bagle call-back proxies, etc.) and dedicated Spam BOTs (such as Cutwail, Rustock, Lethic, etc.), which have been abused to send spam, worms/viruses that do their own direct e-mail transmission, or some types of trojan-horse or "stealth" spamware, dictionary e-mail harvesters, etc.