Hillary has been pleading ignorance for months when it comes to the email scandal with the mishandling of emails as the Secretary of State. There was a non-disclosure agreement signed by her that ackonwledged her responsibility to ascertain whether information shared by her was classified.
Per the Washington Free Beacon:
"As the nation’s chief diplomat, Hillary Clinton was responsible for ascertaining whether information in her possession was classified and acknowledged that “negligent handling” of that information could jeopardize national security, according to a copy of an agreement she signed upon taking the job."
At this point, the Clinton campaign has not responded to any requests for comments. Also, most likely the media will not do much with this, since Hillary runs it. To no one's surprise, this big story was dropped on a Friday.
So why is this such a huge story? Well, this gives an example of how closely she will hold an oath were she to become President of the United States. If she is President, this office and the oath that comes with it will become a joke.