EXCLUSIVE: New details about the emails on Hillary Clinton's personal server that contained classified markings call into question her claim to the FBI that she didn't know what the markings meant -- and even believed they represented an alphabetical listing of paragraphs.

A government source told Fox News that virtually every paragraph in one mail contained so-called portion markings used exclusively for classification purposes. These classified codes are found on the left-hand side and reflect the classification of the intelligence contained in each paragraph. 

The Clinton email has one paragraph marked "C" for "confidential," which is the lowest level of classification. And the source said "multiple paragraphs (on the same email) are marked, SBU," which means "sensitive but unclassified." 

Both codes are there so the reader knows what is classified intelligence.