Bin Laden wrote the text of emails on his computer at his home in northern Pakistan, then had a courier copy it to a thumb drive and send the message from a remote Internet cafe. For incoming emails, the process was reversed. Using this method, bin Laden was able to write a very large number of emails without being electronically tracked.
Although this meticulous way of communicating helped bin Laden stay in hiding for so long, it also helped U.S. intelligence operatives retrieve a huge amount of data. After killing bin Laden, Navy SEALs recovered about 100 flash drives that contained much of his email communication.
The U.S. government has enlisted Arabic speakers from the intelligence community to help examine the contents of the drives. So far, they've discovered a number of email addresses and phone numbers, and the information will likely lead to subpoenas of Internet service providers and additional investigations around the globe.