Tim Ferris in Four Hour Work Week on email:
Email communication should be streamlined to prevent needless back-and-forth. Thus, an email with “Can you meet at 4:00 pm?” would become “Can you meet at 4:00 pm? If not, please advise three other times that work for you.”
Get into the habit of considering what “if … then” actions can be proposed in any e-mail where you ask a question.