Automatically saved drafts of unsent messages

I was typing an email, within populi, to students in my class (from Roster>Email this section). When I was almost finished  - I think I spent about 30min - I pressed Control-R (to try to right-justify some text), not realizing that it would refresh the page, and I would lose everything that I had typed. Can you please add automatic saving of draft messages, to minimize the chance of such issues occurring? Thank you!