It's here now and deleted in a heartbeat. That's what emails are for. Fast and easy whispers over the ether. If you look at emails between individuals, they are not written in the same formal style as a traditional letter. They are briefer, lighter in content and style.
Email is fast, and so is the manner in which it is written and consumed.
It's the junk food of written communication, and we love it. Here, for example, is the reply to an email I sent to Don, a sometime colleague of mine. That was it, exactly. Not even a closing period. Don is a master of the brief email.