Gmail Postmaster Tools for Senders
Google announced new postmaster tools for senders sending to Gmail. The Gmail Postmaster Tools are to help “qualified high-volume senders analyze their email, including data on delivery errors, spam reports, and reputation.” The updated postmaster pages also include Gmail’s best practices for bulk senders.
Postmaster Tools by Gmail http://gmail.com/postmaster
Update: ReturnPath has a blog post that includes data and definitions for each of the data points.