The FBI and the NSA (National Security Agency) has been monitoring email traffic on the Internet for over a decade. The efforts have been sporadic, and largely secret, as new technologies were developed to try and cope with the growing masses of email being generated by the growing popularity of the Internet and the World Wide Web. In the past year, numerous arrests of terrorist suspects were made possible by email intercepts. But on March 30th, Canadian police arrested computer programmer Mohammed Momin Khawaja as part of the round up of eight other men in Britain on charges of planning terrorist attacks. Police mentioned that Khawaja was identified via an intercepted email. This was the first time it was admitted that the NSA was intercepting email. 

Little information has leaked out about how the NSA goes about monitoring the billions of email messages that flood the Internet each day. Network engineers have commented on the complexity of the task, and how it would require some powerful computers, and very clever software, to extract useful information from the flood of data. Basically, the software looks for key words or phrases as well as email addresses and IP locations (every user or server on the Internet has a unique IP, or "Internet Protocol" address, which is similar to a phone number.) U.S. intelligence agencies have had more success in literally tapping a home or internet caf and just capturing emails coming in and out of that location. But trying to mine the entire Internet email traffic, or the majority of it that passes through the United States (thus allowing the NSA to tap into it) is a matter of probability. Only a few messages per million may be useful, and NSA is probably still working up tools that will allow them to scan a growing percentage of that traffic. But even the ability to scan ten or twenty percent of the Internet traffic would provide useful information. Playing the odds like that may have been what led to the arrest in Canada. Once you get a lucky hit like that, you can tap into a specific location and collect a lot more useful emails. The email monitoring program is actually based on an earlier, and still functioning, system that scans phone messages.