Hi Antoine--

thanks for an entertaining and thoughtful read.

Your elisp rendered really strangely for me in notmuch mode in emacs:

     (widen)
     (save-excursion
       (set-buffer output-buffer-name)
       (markdown-add-xhtml-header-and-footer ""))
     (insert "
 [ multipart/alternative ]
  [ text/plain ]
  \n")
      (end-of-buffer)
      (insert "
  [ text/html (hidden) ]
\n") (insert-buffer output-buffer-name) (insert "
 [ text/plain ]
     ;; remove Markdown <pre> markings
     (goto-char signature-position)

(note the []-delimited emacs buttons above)

The issue here appears to be that the MIME boundaries in your message (i
won't repeat them here because i don't want to break my own message) are
getting mixed up/confused somehow with the mime boundaries you include
in the elisp.

I'd be happy to compare raw files with you at some point if you want to
try to make sense of this.  I'm hoping that the error is in the message
generation (that your sending MUA garbled your elisp) rather than in the
receipt, because if the receiving side is at fault it's a much worse
security risk.

On Sun 2019-02-24 20:52:40 -0500, Antoine Beaupré wrote:
> PPS: I remember reading about someone wanting to declare a text/markdown
> mimetype for email, and remembering it was all backwards and weird and I
> can't find the reference anymore. If some lazyweb magic person could
> forward the link to me I would be grateful.

https://tools.ietf.org/html/rfc7763 -- I'm sure Sean Leonard (the author
of this informational RFC) would be open to discussion about what's
missing or what could be improved.

        --dkg