Email (let's drop the hyphen) I have been a happy man ever since January 1, 1990, when I no longer had an email address. I'd used email since about 1975, and it seems to me that 15 years of email is plenty for one lifetime. Email is a wonderful thing for people whose role in life is to be on top of things. But not for me; my role is to be on the bottom of things. What I do takes long hours of studying and uninterruptible concentration. I try to learn certain areas of computer science exhaustively; then I try to digest that knowledge into a form that is accessible to people who don't have time for such study. On the other hand, I need to communicate with thousands of people all over the world as I write my books. I also want to be responsive to the people who read those books and have questions or comments. My goal is to do this communication efficiently, in batch mode --- like, one day every three months. So if you want to write to me about any topic, please use good ol' snail mail ...
-- Prof. Donald E. Knuth's Home Page