Learning to manage e-mail relations with students is much like learning, as a junior instructor or assistant professor, how to manage relations with live students. We all work out a mix of formality/informality, intimacy/distance, seriousness/play in our personal styles. The challenge comes when the new medium seems to shift the balance toward informality, intimacy, and play. Wisdom lies in knowing how to ease gently to a new balance. Luckily, it is easy to ignore the inappropriate message, and your students will soon enough get a sense of how often you can be expected to respond, at what hours, and in what tone.