The Kempt.net DNS Black List
The Kempt.net DNS Black List (DNSBL) operates identically to other such lists on the Internet.
If you are a mail server administrator attempting to remove your host from the black list, please see the Kempt.net spam policy page.
Any known-spam message detected by the kempt.net mail servers will cause the sending host to be listed immediately. Messages are identified by the way in which they are sent and the addresses to which they are sent, not by their content. In this way, no message will be misidentified as spam simply because it matches some criteria for spam-like content. The list does not target any particular spammers or any particular spam messages. The most commonly identified spam messages are those that are sent to one of several email addresses that have never existed in the history of the Internet, and yet which, for some unknown reason, each receive dozens of spam messages a day.
As mentioned above, offending hosts are delisted fairly quickly, with the “penalty” time determined by the number of times this particular host has relayed or originated spam in the past. This way, transient spammers are listed for a short time, and will be delisted once the problem is corrected. Persistent spammers will be listed for a longer time, and will presumably sooner or later show up in many of the larger lists of known open relays or spam sources.