From Seo Wiki - Search Engine Optimization and Programming Languages
DNSWL (DNS-based whitelist) is both a generic term and a specific list. The specific list DNSWL.org, lists over 50,000 legitimate SMTP senders.
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 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.
DNSWL.org has been founded on 1st November 2006 by Matthias Leisi. Legitimate senders can register for free. Most DNS servers are sponsored by various organizations worldwide.
DNSWL.org 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.
- ↑ Matthias Leisi (27 January 2009). "50'000!". http://www.dnswl.org/news/archives/10-50000!.html. Retrieved 16 July 2009.
- ↑ See Bounce message for a discussion about delivery errors, and Backscatter (e-mail) for why they cannot always be noticed to the sender.
- ↑ Matthias Leisi (1 November 2008). "Happy Birthday, dnswl.org". http://matthias.leisi.net/archives/189-Happy-Birthday,-dnswl.org.html. Retrieved 16 July 2009.
- ↑ DNSWL's thanks page doesn't list its sponsors extensively. Robtex's page and whois data at PIR.org are more up to date.