Last year, Yahoo Inc. built a custom software program that searched through its customers' emails for specific information provided by U.S. intelligence officials, according to three former employees. Experts said this represents the first case to surface of a U.S. internet company agreeing to an intelligence agency's request by searching all arriving messages, as opposed to examining stored messages or scanning a small number of accounts in real time.

Article source: http://www.reuters.com/article/us-yahoo-nsa-exclusive-idUSKCN1241YT

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