But some of the emails contain what the government calls “sensitive” information or “SBU’’ — sensitive but unclassified. This includes details of the whereabouts of State Department officials in Libya when security there was deteriorating during the 2011 revolution. One email from a year and a half before the attacks that was marked sensitive but unclassified contained the whereabouts of Mr. Stevens as he considered leaving Benghazi during the uprising against the Qaddafi regime because of the deteriorating security.