Former employees of the email giant Yahoo say Yahoo secretly scanned the contents of hundreds of millions of email accounts and turned the information over to the NSA or FBI. In order to do so, Yahoo secretly built a special software program specifically designed to search every user’s emails for keywords provided by the U.S. government. If true, the practice represents the first known time a giant email company searched all arriving emails in real time at the behest of the U.S. government’s domestic surveillance programs.