Now Playing: 11-14-12 Marketplace Tech Report

Did you see how former CIA director David Petraeus communicated electronically with his biographer and paramour? It is an email technique supposedly favored by terrorists to cover their tracks. Open an email account using, for instance, Google's Gmail.  Write a message, don't send it. Instead, save it as a draft then give your email password to the recipient. She then logs in and reads the message in the draft email folder. The message seems tougher to trace because it's never been sent, like leaving a message in an envelope on your desk and giving the recipient a key to your office.