[RFC] writing HTML email with notmuch

[Antoine Beaupré]

Hi,

TL;DR: magic recipe to include an HTML version when writing plaintext.

I know, I know, HTML email is "evil"[1]. I mostly never ever use it, in
fact, I don't remember the last time I consciously sent HTML. Maybe I
did so back when I was using Netscape Communicator[2][3], but whatever.

The reason I thought about this again is I have been doing more
photography these days and, well, being allergic to social media, I have
very few ways of sharing those photographs with families and friends. I
have tried creating a gallery website with an RSS feed but I'm sure no
one here will be surprised that the uptake is minimal, if
non-existent. People expect to have stuff *pushed* to them, like
Instagram, Facebook, Twitter or Spam does.

So I thought[4] of Email again: the original social network! I figured I
would just make a mailing list, and write to my people once in a while
to let them new about my new pictures. And while writing the first
email, I realized it was pretty silly to not include images, or at least
*links* to images in the email.

I'm sure you can see where this is going. A link in the email: who's
going to click that. Who clicks now anyways, with all the tapping[5]
going on. So the answer comes naturally: just write frigging HTML
email. Don't be a rms^Wreligious zealot and do the right thing, what
works basically everywhere[6] (even notmuch!).

So I started Thunderbird and thought "what the heck am I doing! there
must be a better way!" After searching for "message mode emacs html
email ktxbye", I found some people already thought about this problem
and came up with somewhat elegant solutions[7]. I built on that by
trying to come up with a pure elisp solution, which goes a little like
this:

(defun anarcat/notmuch-html-convert ()
  """create an HTML part from a Markdown body

This will not work if there are *any* attachments of any form, those should be added after."""
  (interactive)
  (save-excursion
    ;; wrap signature in a <pre>
    (message-goto-signature)
    (setq signature-position (point))
    (forward-line -1)
    ;; GFM markers for pre, used because easier to undo than the
    ;; "prefix by 4 characters" standard
    (insert "```")
    (end-of-buffer)
    (insert "```")
    ;; set region to top of body then end of buffer
    (end-of-buffer)
    (message-goto-body)
    (narrow-to-region (point) (mark))
    ;; run markdown on region
    (setq output-buffer-name "*notmuch-markdown-output*")
    (markdown output-buffer-name)
    (widen)
    (save-excursion
      (set-buffer output-buffer-name)
      (markdown-add-xhtml-header-and-footer ""))
    (insert "
-------------- next part --------------
\n")
    (end-of-buffer)
    (insert "
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://notmuchmail.org/pipermail/notmuch/attachments/20190224/56f408d2/attachment.html>
-------------- next part --------------
    ;; remove Markdown <pre> markings
    (goto-char signature-position)
    (while (re-search-forward "^```" nil t)
      (replace-match ""))))

For those who can't read elisp for breakfast, this does the following:

 1. parse the current email body as markdown, in a separate buffer
 2. make the current email multipart/alternative
 3. add an HTML part
 4. inject the HTML version in the HTML part

There's some nasty business with formatting the signature correctly by
wrapping it in a <pre> that's going on there - I took that from
Thunderbird as well.

(For those who *do* read elisp for breakfast, improvements and comments
on the coding style are very welcome.)

The idea is that you write your email normally, but in markdown. When
you're done writing that email, you launch the above function (carefully
bound to "M-x anarcat/notmuch-html-convert" here) which takes that email
and adds an equivalent HTML part to it. You can then even tweak that
part to screw around with the raw HTML if you feel depressed or
nostalgic.

What do people think? Am I insane? Could this work? Does this belong in
notmuch? Or maybe in the tips section? Should I seek therapy? Do you
hate markdown? Expand on the relationship between your parents and text
editors.

Thanks for any feedback,

A.

PS: the above, naturally, could be adapted to parse the body as RST,
asciidoc, texinfo, latex or whatever insanity you think would be more
appropriate, I don't care. The idea is the same.

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.

 [1]: one of so many: https://www.georgedillon.com/web/html_email_is_evil_still.shtml
 [2]: https://en.wikipedia.org/wiki/Netscape_Communicator
 [3]: yes my age is showing
 [4]: to be fair, this article encouraged me quite a bit:
 https://blog.chaddickerson.com/2019/01/09/replacing-facebook/
 [5]: not the bass guitar one, unfortunately
 [6]: https://en.wikipedia.org/wiki/HTML_email#Adoption
 [7]: https://trey-jackson.blogspot.com/2008/01/emacs-tip-8-markdown.html