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.
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.