On Sun 2020-03-29 17:53:01 -0700, Carl Worth wrote:
> On Mon, Mar 30 2020, Brian May wrote:
>> This applies to all 4 of those messages. Yes, they all look like they
>> have the same Message-ID
>
> 4 different messages all with the same message ID definitely violates a
> core assumption of notmuch (that each message as a unique message ID).

Well, not if they're actually all the same message, right?

Brian, can you confirm whether the body of these 4 messages are the same
or not?  (e.g. you might have gotten different copies due to receiving
mail at different e-mail addresses, or through a mailing list, or just
through an SMTP hiccup)

> I think it would be reasonable to state that the behavior of notmuch is
> officially "undefined" in that case.

What about for a message that References: its own Message-ID:?  Do we
expect to handle that case sensibly?  I'm not sure where i'd look in the
test suite to confirm that we intend to make that work OK, and i can
definitely imagine that being a goofy corner case when trying to
manipulate threads.

       --dkg