Am Mo., 25. Sept. 2023 um 12:53 Uhr schrieb Teemu Likonen <>:
> * 2023-09-25 11:54:07+0300, Teemu Likonen wrote:
> > Some person on debian-user mailing list seems to be sending messages
> > with fixed Message-ID field: the same ID in different messages. In
> > Notmuch it is creating trouble because it connects unrelated threads to
> > one. The person has different messages in different threads but Notmuch
> > thinks they are the same message because the Message-ID is the same.
> >
> > This is potentially a "denial of service" for Notmuch. Well, not quite,
> > but is harmful nonetheless. How would a Notmuch user fix the mess or
> > protect himself against it?
> I am no longer sure if this issue is caused by fixed "Message-ID" or
> wrong "References" or "In-Reply-To" values. Anyway, someone has created
> real mess anyway because Notmuch combines originally separate threads
> now and forever.

Yes, several sources of different badness ...

Still, if I understand correctly, a new message with a pre-existing
mid ends up being registered by notmuch as a second file for the
"same" message irrespective of differences in the actual files. For
message copies which you receive via different paths (say directly
plus via an ml) this may or may not be what you want. Used
intentionally, it may create harm - how do other mailers handle this?
Show them in parallel in the same thread (but as individual messages)?

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