I sometimes use the LibreOffice File -> Send -> Email as PDF or the "Email" option most file managers now provide.  Emacs (or emacsclient) correctly invokes notmuch-message-mode; however the header is nonfunctional

    From: Some user <someuser@host.org>
    To:
    Subject:
    Attachment: /home/user/path/document.pdf

The bug is the nonfunctional "Attachment: /home/user/path/document.pdf".  It seems to me that that path should be passed to mml-attach-file.  Alternatively, if this is something that the user needs to configure then text to that affect should appear in the buffer and/or in the echo area.

Best,
Nicholas

P.S. I'm reporting this from a trixie system because I'm guessing the "-2" in forky is just a rebuild plus some packaging-correctness stuff.

Nicholas D Steeves <sten@debian.org> writes:

This is a reasonable feature request; I've marked it as wishlist to manage
expectations.

I'm not familiar with this "Attachment" header, but possibly I just
missed some evolving defacto standard. If you know any RFC like
description (maybe in the mailto URL RFC), that would be interesting.

It depends whether you are running the backport of 0.40 or 0.39 as
reportbug claims. In either case I suspect it would not change the
behaviour you mention.

The message-templ package (elpa-message-templ in Debian) provides some
tools for customizing message-mode. `message-templ-config-alist` in
particular allows running code based on the presence of headers. This
might be simpler than starting from scratch.