Many thanks John for this email and also for your very useful videos. As I told you, I use sometimes gnus + org-mode to make roughly the same things that you make with m4ue. Your message appears correctly in two formats in gnus: multipart/mixed and text/html. In a browser used with gmail its html is perfect.
I confess that I do not succeed to use only gnus for my email, but mainly when it is more convenient for professional reasons. Unfortunately, I have not still succeed to use gnorb, because I do not understand clearly how it works. But even without gnorb, gnus works well in harmony with gmail in IMAP. Maybe some people in this list could share their experiences with an emacs email client + org-mode and help to make the better choice, if possible? Best wishes, Jo.