viewing duplicate messages

[drebs]

Hello, sorry for breaking the thread but i just subscribed to this list.
This is a response to:
https://notmuchmail.org/pipermail/notmuch/2019/028189.html

On Thu May 30 16:02:57 PDT 2019, dkg at fifthhorseman.net wrote:
> If you'd care to forward me a zipfile containing examples of at least
> two distinct messages with the same message ID, i'd love to look through
> a copy of this sort of confusion.  It's good to understand the different
> ways these sort of things go wrong.
> 
>     --dkg

I've bounced into this problem when using notmuch-emacs to interact with
a schleuder list (https://schleuder.org).

I know it's very specific, looks like an usability issue more than
anything, and I'm not very sure it should be considered as a notmuch or
a schleuder issue, but I think it's worth to describe it here to have it
noted and maybe get feedback.

---

When I send a message to a schleuder list, it is first encrypted to the
list's OpenPGP certificate before leaving my computer. Schleuder will
then decrypt it and re-encrypt to the subscribers' certificates, and it
will maintain the Message-Id untouched.

After i receive my own message back from the list, I will end up with
2 different files in my maildir having the same Message-Id: the first
one is the message i sent which is encrypted to the list's cert and the
second one is the message the list sent back to me encrypted to my own
cert.

Looks like from notmuch doc that notmuch search counts those 2 files as
the same message, and it shows me that there is 1 match but 2 files (in
parenthesis). notmuch show also shows me the first message only. If
i list --output=files I'll get both files as result.

Problems are:

    1. notmuch-emacs displays to me the message I sent, and that one
       I can't decrypt because it's encrypted to the list's cert.

    2. notmuch does not tag the incoming message as new, so it's hard to
       notice when/if the message has arrived back from the list.

---

Some workarounds I thought:

    - encrypt the outgoing message also to myself, solves (1) but not
      (2).

    - using a post-new hook to find out when the message has been sent
      back and do *something* so notmuch will tag and show the "correct"
      one for me. (thanks to Defolos in IRC; still have to come up with
      *something*)

I wonder if someone goes through the same issue and has comments or
solutions to this.

Sorry that I can't provide a copy of the messages, but I hope the
description is explanatory enough.