> Side note #2, I think we should provide *all* versions of reply-headers
> (reply-to-sender, reply-to-all, mail-followup-to, whatnot) in the
> formatted output, and let the user toggle between them in notmuch-emacs
> while composing the reply.

I did post a series doing some of this many years ago

id:1368303344-13713-1-git-send-email-markwalters1009@gmail.com

I don't know how much work it would be to get that into shape (the patch
even mentions JSON rather than sexp).

Best wishes

Mark