What is dnswl.org?

Dnswl.org is the leading email whitelist, also called DNS whitelist (DNSWL).

Dnswl.org provides reputation information about email senders. It has close to 100’000 users (companies, organisations and individuals) with tens of thousands of requests per day, and contains over 300’000 entries of “good mailservers”, including a fast growing amount of IPv6 entries.

Beyond the 100’000 large users, dnswl.org is used by more than 4 million distinct IP addresses with low query volumes on a daily basis.

Your email filter should try to avoid tagging messages as spam if they come from one of the good mailservers we list, which are assigned into one of four trust levels:

Trust Level Description
High Highly unlikely to send spam, and expected to be very fast in remediating issues.
Medium Rare spam occurrences, corrected promptly.
Low Occasional spam occurrences, actively corrected but less promptly.
This is the default for most categories.
None These are legitimate mail servers, but they may also emit spam or have other issues from time to time.
This is the default for some categories (eg Email Marketing Provider).

What does it cost?

Access for non-commercial users doing fewer than 100’000 queries per day is free. See the license page for details.