Package: mh-e Version: 8.5-2 After a system upgrade I see that mh-e (8.5-2) now displays inline images and HTML mail using external viewers in emacs (24), but not without problems.
When it displays the file, it marks the file as modified---so after viewing such a message, you have to confirm to discard changes with this message in the minibuffer: "Message TK modified; discard changes? (yes or no)."
