An incredible map of which countries e-mail each other, and why?

The Internet was supposed to let us bridge continents and cultures like never before. But after analyzing more than 10 million e-mails from Yahoo! mail, a team of computer researchers noticed an interesting phenomenon: E-mails tend to flow much more frequently between countries with certain economic and cultural similarities.

see the paper in Washington Post

original paper: State et al. 2013 World internet