It should be possible to save an email you've already typed up but need to do a quick check before sending. Currently the template is cleared whenever changing tabs.
Thanks for your question. I agree that it is an annoyance when you work in web based applications that text is lost when switching tabs or going back and forth. We are looking into ways of solving this for the top rated parts of projectplace. I think at the moment, text is for instance saved in the comments for documents even if you switch between tabs.
Depending on the number of votes for this area, we will discuss whether this is possible to improve for the emails aswell.