SMTP mails without Message-Id

[kkretsch]

With the current 0.13.0 version I added SMTP configuration in the config file. Running as docker compose stack.

Sending eMails with these settings works.
When I use the reset password functionality my uplink mail server (mailu) complains a missing Message-Id header in the incoming email, which gives a negative impact on rspamd.

In my opinion the Message-Id should be generated already by the sending system (here lemmy).
Otherwise it got added by my final destination mail server, but the intermediate mailu server had that complaint.

[Nutomic]

Do you have any link which explains how to implement such message ids in a webserver?

[kkretsch]

In RFC822 https://www.w3.org/Protocols/rfc822/ it is somehow described.

It ends up in a free to choose msg id format like:

Message-ID: <something-like-an-UUID-perhaps@my.lemmy.domain>

And the two letters ID are both uppercase, which is checked by some spam daemons too.