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DNSWL: Wikis


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From Wikipedia, the free encyclopedia

DNSWL (DNS-based whitelist) is both a generic term and a specific list. The specific list, lists over 50,000 legitimate SMTP senders[1].


Generic need for whitelisting

Natural language understanding is not a mature field. Common computer processes used for spam filtering apply heuristics to avoid presenting too many useless messages to email recipients. This has the severe impact of reducing SMTP reliability[2] by creating false positives, i.e. silently dropping legitimate messages. Whitelists tackle the task of vouching for a sender, which implies identifying an accountable party that the sender belongs to. has been founded on 1st November 2006 by Matthias Leisi[3]. Legitimate senders can register for free. Most DNS servers are sponsored by various organizations worldwide[4]. lists IP addresses, but also hold domain names, category, and email contact addresses. Each IP address is given a "trustworthiness" level; applications, e.g. SpamAssassin, typically decrease the "spamminess" score of a message by a value proportional to that level.

See also


  1. ^ Matthias Leisi (27 January 2009). "50'000!".!.html. Retrieved 16 July 2009.  
  2. ^ See Bounce message for a discussion about delivery errors, and Backscatter (e-mail) for why they cannot always be noticed to the sender.
  3. ^ Matthias Leisi (1 November 2008). "Happy Birthday,"., Retrieved 16 July 2009.  
  4. ^ DNSWL's thanks page doesn't list its sponsors extensively. Robtex's page and whois data at are more up to date.

External links



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