How did email grow from messages between academics to a global epidemic?

Ray Tomlinson, the man who invented the @ sign, has died. Here's a brief history of email, from the Queen's first mail to the triumph of spam

Ray Tomlinson, the man who literally put the "@" in email, died on Saturday, but his invention, which allowed electronic messages to spread across the internet and fill our lives and our inboxes on a daily basis, will live on.

Here is a brief look at what Tomlinson started and the evolution of email through the last half-century.