@josemanuel In fact, while reading mail I usually capture to org-mode and author my response (most of my email is authored in org-mode). I use org-mime to htmlize the buffer and open a multipart ascii / html message ready to send. When I do send, it goes to a local postfix server that relays via smtp for for multiple accounts, giving me offline sending support.
@josemanuel I used to use mutt, but I but now I'm happy using mu4e inside emacs.