My mail was not delivered because “Message-ID header in the email has been modified” according to response from ps@zoethical.com
According to my research
Message-ID header header field was present in original message
Message-ID header field was missing in response
original Message-ID header was not preserved in any form in response
Message-ID header field is optional
Message-ID header is supposed to be unique per message, not message thread according to Message-ID wikipedia article (new user, unable to link it) so preserving it would be incorrect anyway
What is my mail client supposed to do to be able to deliver the mail message? I am asking as I plan to make a bug report/feature request to Tutanota developers but I am unsure what exactly my mail client is supposed to do.
Your message was successfully delivered to my email but indeed not to our Discourse instance.
ngi0-mentor is an alias that enables testing this kind of usage where a group can handle incoming email with Discourse. It is also delivering to a direct email address to avoid losing messages. I am not sure yet how to handle this since it could be anywhere from Tutanova to Discourse, but I suspect I sent you the original message from a mail client outside Discourse, and it detected your response as a reply to something it did not know. I think the best is to report to the Discourse team and see what they think. I will do that ASAP, but there’s no urgency on your side: if your using regular SMTP, I’m pretty sure the problem comes from Discourse.
We can check together and try to reproduce in the next few days. My take is that:
I send you an email from a regular client
You reply to it
Discourse fails to recognize the original Message-ID since it does not have it.
If that fails according to specs, then we know what we’re dealing with. Otherwise we need to investigate your mail setup. 90% it’s on my side though. Don’t sweat it!