Internet Security Threats: Who Can Read Your Email? by Mark Brooks
Before being able to choose a secure Internet communication system, you need to understand the threats to your security. Since the beginning of the Internet there has been a naive assumption on the part of most email users that the only people who are reading their email are the people they are... The privacy of your Internet communications has now become the front line in a struggle for the soul of the Internet. ... Each one of these hops is a separate network, often owned by a different Internet Service Provider (ISP).