Don't e-mail messages you don't want others to read. It is less private and secure than sending letters. In fact, copies often stay in the computer system long after you think you have deleted the message.
You don't want to be known as a "junk e-mailer," so be careful who you send your messages to. The more junk you send, the more you'll be ignored.
Keep your e-mail short. Most folks find it uncomfortable--and difficult--to read long messages on screen.
Finally, don't let e-mail take the place of personal contact. Many situations call for the more personal phone call or face-to-face meeting.
Excerpted from Get Smart: 365 Tips To Boost Your Entrepreneurial IQ