Delivering to usanet does not publish either connection or sending limits.

Important links and references

Postmaster pages does provide a postmaster website for senders.

Feedback loop does provide a feedback loop.

Whitelist does not provide a whitelist for senders.

Certification Services uses the Return Path Certified whitelist in mail delivery decisions. Mail from IPs on the Return Path Certified list will see better delivery at

Support for Senders provides an IP lookup form on their postmaster site. They do not provide any public contact paths.

Known spamfilters started using Cloudmark products to filter mail in early 2010. 1