Re: multipart/related; not multipart/mixed; RFC 2387; html, embedded png

[Uwe Brauer <oub@mat.ucm.es>]

>> On Tue, 10 Apr 2012 20:41:28 +0200, Lars Magne Ingebrigtsen <larsi@gnus.org> wrote:

   > Uwe Brauer <oub@mat.ucm.es> writes:

   > If it's an HTML message that includes an image, then multipart/related
   > is correct.


Well fine, but my point is: gnus does *not* do the correct
thing!!!
It inserts 
Content-type: multipart/mixed; boundary="=-=-=" 
in the header, so this seems a bug or, at least, a  missing feature.

The only way I solved this issue was to change 

(defun mml-generate-mime ()
  "Generate a MIME message based on the current MML document."
  (let ((cont (mml-parse))
	(mml-multipart-number mml-multipart-number))
    (if (not cont)
	nil
      (mm-with-multibyte-buffer
	(if (and (consp (car cont))
		 (= (length cont) 1))
	    (mml-generate-mime-1 (car cont))
;	  (mml-generate-mime-1 (nconc (list 'multipart '(type . "mixed"))
	  (mml-generate-mime-1 (nconc (list 'multipart '(type . "related"))
				      cont)))
	(buffer-string)))))

But that seems to me a very ugly solution and besides it
might cause some inconvenience which I am not aware of. I
don't understand the structure of mml, so I don't know what
really to suggest. 

I would introduce a new variable 
mml-mime-use-related
and wrap into the mml-generate-mime function.

Then I would modify the org-mime-htmlize function such that
it sets mml-mime-use-related to t, and finally I would
insert a function into the send hook which would reset the
variable again to nil.

I presume there are much more elegant solutions.