dnswl.org

DNSWL.org provides a Whitelist of known legitimate email servers to reduce the chances of false positives while spam filtering. We effectively divide the entire Internet up (by IP) into five categories, and provide you with efficient access methods to this data for free.

Trust Level	Description
High	Never sends spam.
Medium	Extremely rare spam occurrences, corrected promptly.
Low	Occasional spam occurrences, actively corrected but less promptly.
None	Legitimate mail server, may also send spam.

If you know of IP addresses which we have miscategorized please tell us. Your input is our motivation for maintaining this service.

There is no business model associated with dnswl.org. It is believed that this service can be maintained by volunteers. We believe that it is easier and more effective to cooperatively maintain a single whitelist than for each of us to manually maintain our own separately.

Of course you may use this data to filter however you like. Our general recommendations are:

Skip greylisting for all listed IPs (none - high)	All listed hosts are expected to pass greylisting so you are only avoiding delays, not affecting what gets blocked.
Skip blacklisting for all listed IPs (none - high)	All listed hosts are known to send legitimate email and should not be blacklisted.
Skip spam filtering for medium and high ranked IPs.	These are trusted to send spam rarely enough that they are not worth filtering.
Never skip virus filtering.