USA.net

Delivering to
USA.net does not publish  either connection or sending limits.

Postmaster pages
USA.net does provide a postmaster website for senders.

Feedback loop
USA.net does provide a feedback loop.

Whitelist
USA.net does not provide a whitelist for senders.

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

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

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