I have been suffering from the same problem. The solution I prefer is to disable auto-save-mode in mu4e-compose so that drafts do not accumulate.
(add-hook 'mu4e-compose-mode-hook #'(lambda () (auto-save-mode -1)))
Plus obviously, set mu4e-sent-messages-behavior to delete, as suggested by previous answers (especially in Gmail since Gamil takes care of ...
If t, use message sender to find an OpenPGP key to sign with.
This set the key to match the From: for me. You can customize that variable too (and turn off the guided mode).
Pressing g followed by a number should open the link in the default browser AFAIK. The problem is how to open links in HTML format.
One way to do this is to create a hash table of all links in the buffer containing the URL and a number assigned to it (similar to how mu4e~view-make-urls-clickable works) by searching href anchor properties. There's no general ...