Q:

Disable openwith during execution of a mu4e function

Hi I'm using openwith to open pdf files in okular, the relevant lines are
(require 'openwith) ;open files with external program                                                                                                                                                                            

(setq openwith-associations '(("\\.pdf\\'" "okular" (file)))) ;use okular for pdf                                                                                                                                                
(openwith-mode t)

When I want to send out a message with mu4e though if there is attached a pdf, instead of completing the function message-send-and-exit, the pdf opens in okular and the message is never sent. 
I was thinking of adding a hook the like
(add-hook 'message-send-and-exit (openwith-mode nil))

but I'm not a lisp expert and this doesn't solve the problem, probably I'm doing something wrong, anyone can give me a hint? 

A:

Openwith can interfere with attachments.   Since mu4e reuses message mode, you can do the following to avoid the clash:
;; prevent <openwith> from interfering with mail attachments
(require 'mm-util)
(add-to-list 'mm-inhibit-file-name-handlers 'openwith-file-handler)

