On Thu, May 25, 2023 at 10:24:52AM +0200, Eike Rathke wrote: > > Semantically, the angle bracket characters are not part of the > > msg-id; the msg-id is what is contained between the two angle bracket > > characters. > > *Semantically* > MUAs don't interpret semantics of header fields.
The original question in this thread was about semantics. Also, I'd argue that extracting the Message-ID in order to implement threading is about interpreting the semantics of the Message-ID. > Whatever the brain semantically might mingle there, it's not an excuse > to omit the angle brackets. The syntax requires them to be present and > 3.6.4 is clear on that: Yes, the original MUA is 100% wrong on that point. The question here is whether Mutt should compensate for it (see "Robustness principle"). If Mutt is extracting the Message-ID from a message, should it store the angle brackets as part of the ID? Semantically, the angle brackets are not part of the ID as described above. Whereas syntactically they are part of the msg-id as specified in the syntax diagram. imc
