warsaw u.s. president barack obama say saturday concern state department handle classify information cast part government-wide challenge age email texts smartphones fbi director jam comey tuesday recommend prosecute hillary clinton aid extremely careless handle classify information private email server use secretary state comey say fbi find evidence security culture state department general respect use unclassified systems particular generally lack kind care classify information find elsewhere u.s. government ask fbi director assessment obama tell reporters news conference concern advent email texts smart phone generate enormous amount data obama add say turn put enormous pressure department sort classify properly obama say one classify much benefit information evaporate take long process reflect large problem government add clinton say use private email server mistake obama 'concerned u.s. state department handle classify information