DNSWL (DNS-based whitelist) is both a generic term and a specific list. The specific list DNSWL.org, lists over 150,000 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.
For IPv6, blacklisting is not a realistic option, because of the greatly increased addresses. So whitelisting can be used to reduce a huge address space to a set of manageable size: first build a global whitelist of IPv6 registered senders, and second blacklist within that. By accepting all authentic sender registration request, it is at least possible to eliminate spambots.[3]
DNSWL.org
DNSWL.org was founded on 1 November 2006 by Matthias Leisi.[4] Legitimate senders can register for free. Most DNS servers are sponsored by various organizations worldwide.[5]
DNSWL.org lists IP addresses, but also holds 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
References
- ^ Matthias Leisi (27 January 2009). "50'000!". 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.
- ^ Paul Vixie (7 June 2011). "Two Stage Filtering for IPv6 Electronic Mail". CircleID. Retrieved 17 June 2011.
- ^ Matthias Leisi (1 November 2008). "Happy Birthday, dnswl.org". 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.
External links
