Local save of mass email editor content, just like support tickets

I am really tired of spending lots of time creating an email to send to all customers using the mass mail tool and then when I hit send, there is some sort of error (cache_miss this time) , the send fails and the content of the email is lost. It happens just about every time.

The feature in support tickets where it progressively saves a reply is really great. How about adding the same feature to the mass mail tool?