...The program is designed to look for indicators of cyber attacks by digging into all Internet communications, including the contents of emails, according to the declassified summary.
http://blogs.wsj.com/digits/2010/03/02/“einstein”-program-disclosed-as-us-cyber-shield/
http://blogs.wsj.com/digits/2010/03/02/“einstein”-program-disclosed-as-us-cyber-shield/