The discussion revolves around filtering out delivery status failure emails in Discourse. carlokok shares an issue where 200 failure emails were posted after a mailing, and seeks suggestions to filter them out. codinghorror points out that such emails should be filtered due to the Auto-Submitted header, and shares a link to a GitHub wiki for detecting autoresponders.
However, carlokok finds that many systems do not follow these guidelines, and shares examples of different headers and content types used by various email systems. They also mention that setting up a sieve filter to block mailer-daemon and postmaster emails can reduce the issue.
zogstrip announces an improvement to Discourse’s auto-generated email detection, and DeanMarkTaylor suggests that this might complete a feature request to filter out out-of-office replies in the reply-by-mail feature.
Yep, they should be filtered already because they have a header state of Auto-Submitted
Looks like there’s a lot of broken systems out there then 
I see mails with X-Auto-Response-Suppress: All (from exhange)
Some just have:
Content-Type: multipart/report; report-type=delivery-status;
boundary="110e4b6c-159b-4262-b2ca-cbe359515e6a"
as content type (and no other identifying headers)
QMail just sends a reject mail from From: MAILER-DAEMON@somedomain or From: mailer-daemon@somedomain.
Another one: X-QQ-HolidayReply: true
(I setup a sieve filter to block mailer-daemon & postmaster locally which cuts down 99% of these btw)
Just improved our auto generated email detection 
https://github.com/discourse/discourse/commit/6c82fbebf5fe2912d534d7eb73c35227443457de
@zogstrip you might have completed a feature here:
https://meta.discourse.org/t/filtering-out-out-of-office-replies-in-the-reply-by-mail-feature/8615