Feb 5 (Reuters) - An email system used by Elon Musk and his associates to contact all U.S. federal employees operates "entirely on government computers" and does not use a non-government server, Office of Personnel Management officials said in a court filing on Wednesday. The court filing comes amid growing concern that Musk's associates are flouting security protocols when handling personal information and data as they work to cut staff across the U.S. government. An attorney representing unnamed employees of OPM, the U.S. government human resources agency, asked a judge on January 27, opens new tab to issue a temporary...