The Kempt.net DNS Black List (DNSBL) is a fast-acting IP-based blocklist that focuses on listing new spam sources for a short, temporary period, making it a useful complement to larger, more established blacklists.
The Kempt.net DNS Black List (DNSBL) is an IP-based blocklist with a unique approach to identifying and listing sources of spam. Its primary goal is to react very quickly to new hosts used for spamming purposes, rather than maintaining a long-term list of known offenders. It is designed to be a fast, responsive blacklist that catches transient and newly-active spam sources.
The listing policy is automated and is not based on email content. Instead, it identifies spam by the way messages are sent and the addresses they are sent to. For example, it monitors email sent to addresses that have never existed but still receive high volumes of spam. When a message from a new source is detected sending to these spam-trap addresses, the sending IP address is immediately added to the blacklist.
Some key technical aspects of this blocklist include:
The Kempt.net DNSBL was operated by Kempt.net, which was an Internet Service Provider (ISP). The company provided services such as email, web hosting, and shell access. Based on available information, the ISP no longer appears to be operational, but the DNS blocklist may still be in use by some mail server administrators.
Removal from the Kempt.net DNSBL is an entirely automated process. There is no manual delisting form or contact email for removal requests.
An offending IP address is listed almost instantly after it is caught sending spam. The delisting process is time-based:
To be delisted, you must first identify and resolve the issue that caused your IP to send spam. Once the problem is corrected, you simply have to wait for the automatic expiry of the listing. This system ensures that transient issues are resolved quickly, while persistent spammers remain on the blocklist for longer periods.
The impact of being listed on the Kempt.net DNSBL is generally considered low. Because the blacklist is designed to be transient and focuses on a small number of newly-active spam sources, its adoption is not as widespread as larger, more established lists. Furthermore, the automatic delisting policy means that any impact is temporary, especially for a first-time offense.
However, if a mail server you are sending to does use this particular blocklist, your emails will be rejected for the duration of the listing. This will result in bounced emails and prevent your messages from reaching their intended recipients at that specific provider.
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