How to reject an email using mailgun?

Question

Does anyone know how to reject an email received through mailgun (mailgun.com)? As a comparison, a similar service, cloudmailin allow you to return a status code of 404 or 403 to reject an email, and the sender of that email will receive a delivery failure notice. I am trying the same with mailgun, however, mailgun will attemp to redeliver with longer and longer interval once it receive the 404 or 403 status code.

What I have tried: Mailgun documentation doesn't say anything about this. Mailgun support is not responding to my emails.

If I got an answer from mailgun I will post it here as an update.

Answer 1

Your app could return 406 code to mailgun to stop retrying. We added that feature recently and haven't yet updated our documentation regarding that.