Show us the sender score/reputation.
Reputation is everything in email delivery.
From your own documentation: "One of the most important assets you have in the email world (much like the real world) is your reputation. If you do not have a good reputation tied to your domain and your IP address (“IP” used herein for abbreviation), your email will not reach your recipients’ inboxes." (https://documentation.mailgun.com/best_practices.html#reputation)
It'd be nice to access the sender score [on a per domain basis] through the API. Knowing that info, directly, would give domain holders the warm fuzzies on their reputation without having to go elsewhere (senderscore.org).
Marco @ mailgun requested I write this here. Hi Marco! :) This is per support ticket #226672.
Anthony Amolochitis commented
I am always watching my sender score.