Have to recommend a blog by Richard 'Dick' Lipton called "Godel's Lost Letter and P=NP." Lipton is Professor Emeritus at Princeton University now at Georgia Tech in Atlanta. One of his posts, called "Is it time to stop malware - forever?" outlines the history of email, which is fascinating. Here's an excerpt:
In the beginning there was ARPANET. Of course before the beginning there was nothing, but thanks to Bob Kahn and his colleagues the ARPANET was created about fifty years ago. This was the first time computers could send and receive messages and files from each other—it seems so obvious today, but then it was a ground breaking application.
I recall watching with envy my colleagues, like Anita Jones, check her ARPANET account for messages. Since at the time I was not funded by ARPA, I was not able to get an account; hence, no messages for me.
Eventually, those of us on the outside, those of us without ARPANET accounts, decided to act. The key event happen during the summer of 1977, when Rich DeMillo and I spent two month visiting Larry Landweber at Madison. Larry wanted to get out of theory, he was trained in recursion theory, and get into some more system area of computer science. After many discussions, we converged on the project of creating an ARPANET type system that would connect US theorists together.
DeMillo, who is a great and fast writer, sat down and wrote a draft of the proposal in a day or two. For a variety of reasons, Larry became the PI of the proposal: he submitted it to NSF, he got the project funded at Madison, and TheoryNet was born. This became successful quickly, and led NSF to create NSFNET. Thus, we went from email for few—those who worked for ARPA—to email for some theorists, to email for all NSF scientists, to eventually email for everyone.
I have no doubt we would have email today even if Rich and Larry had not started TheoryNet in 1977, but they did create TheoryNet. And it led directly to NSFNET, and so on.
In case you want to know more about recent directions in theoretical computer science, you would do well to check out his blog when he posts. In it, you can read through fascinating entries to learn more about current and historical breakthroughs in computer science from an expert. This email pioneer humbly subtitles his blog "a personal view of the theory of computation" although he could say "Theory of Computation from an Inventor of Email, the world-renowned Computer Scientist, Richard Lipton" but that would be far too flashy for his style. Reading it makes us all smarter about computer science.