Error handling for SMTP errors

Summary

When receiving error responses from other transport agents or delivery agents, they don't seem to be marked as anything more than an "info" log.

I'd like to manage and re-queue these as needed, but they no longer exist in Queue Manager.

Should these be showing as Error or Information?
Is there a Queue Manager but for failures? Pending retry?
A configuration option for postmaster address for notifications?

Some Examples

relay=hotmail-com.olc.protection.outlook.com[104.47.8.33]:25, delay=2.5, delays=0.12/0.03/2.1/0.25, dsn=5.7.1, status=bounced (host hotmail-com.olc.protection.outlook.com[104.47.8.33] said: 550 5.7.1

relay=mail.protection.outlook.com[104.47.71.138]:25, delay=0.96, delays=0.02/0.02/0.76/0.16, dsn=5.4.1, status=bounced (host mail.protection.outlook.com[104.47.71.138] said: 550 5.4.1 Recipient address rejected: Access denied. AS(201806281) (in reply to RCPT TO command))

E927D830AB: relay=smtp.office365.com[52.98.3.178]:25, delay=1.1, delays=0.13/0.02/0.56/0.37, dsn=5.2.0, status=bounced (host smtp.office365.com[52.98.3.178] said: 554 5.2.0 STOREDRV.Submission.Exception:SendAsDeniedException.MapiExceptionSendAsDenied; Failed to process message due to a permanent exception with message Cannot submit message.

Motivation

An extension to Queue Manager that helps diagnose SMTP failures.

Additional context

We use mailcow for an application service, so we'd like to surface SMTP errors centrally for remediation.

Thanks for all your effort #teammailcow 🐮🤠❤

mailcow / mailcow-dockerized