From: Kirill A. Korinsky <kirill@korins.ky>
Subject: Re: Adding Message-ID to mail(1)
To: Christian Schulte <schulte.it@gmail.com>, tech@openbsd.org
Date: Sat, 31 Aug 2024 14:18:39 +0200

On Sat, 31 Aug 2024 11:12:24 +0200,
Stuart Henderson <stu@spacehopper.org> wrote:
> 
> It is standard in most MTAs (including opensmtpd) to add missing
> Message-ID at least to emails which they consider as locally originated.
> (Doing this for mail from external origins risks DKIM failure with some
> header signing setups).
> 

More of that. RFC 6409 requires that the MSA should add Message-ID, or
replace it when it is invalud, see Section 8.3.

-- 
wbr, Kirill