In the heat of the moment anything can happen. Maybe your boss just emailed you to let you know that you have to come in and work on Saturday. Or maybe your girlfriend just dropped you a line to tell you that the dog had an accident all over your side of the bed. You just never know what you might open up your email to find, and you need make sure you prepare your responses accordingly.
Fortunately for all of us short tempered hot heads, there is Tone Check. Think of Tone Check as a spell check for your anger. Maybe you are smart enough to know on your own that telling your boss he has a stupid face is not the best career decision, but if you are not, Tone Check will remind you. Also, it will spell check your email. The best of both worlds!