We also couldn't go with Mailgun for SMTP gateway because of this shortcoming, although we liked the overall feature offerings.
Besides the major issue outlined in the original post (individual users not getting any feedback for warnings/errors), our mailing list software also needs to process bounces directly (which is pretty typical, I think). There are webhooks, but integrating those into a perfectly working list server is considerable work. And furthermore the list server would still need to process asynchronous bounces anyway.
We also couldn't go with Mailgun for SMTP gateway because of this shortcoming, although we liked the overall feature offerings.
Besides the major issue outlined in the original post (individual users not getting any feedback for warnings/errors), our mailing list software also needs to process bounces directly (which is pretty typical, I think). There are webhooks, but integrating those into a perfectly working list server is considerable work. And furthermore the list server would still need to process asynchronous bounces anyway.
Here's an example implementation (sorry for competitor link): https://help.socketlabs.com/docs/my-application-already-handles-bounces-how-do-you-support-this
Cheers.
Dupes:
https://feedback.mailgun.com/forums/156243-feature-requests/suggestions/12365664-error-fail-bounce-and-reply-mails-back-to-sender
https://feedback.mailgun.com/forums/156243-feature-requests/suggestions/34411840-customizable-mail-from-return-path-address
Possible dupe: https://feedback.mailgun.com/forums/914635-general-feedback/suggestions/8010573-add-bounce-and-complaint-route-actions
Related: https://feedback.mailgun.com/forums/156243-feature-requests/suggestions/6345497-forwarding-of-auto-responses-sent-to-the-return-pa