Here is the US Code Mrs Clinton violated, word for word. The Secretary of State needs to know military information. It is to be handled in a manner prescribed by law. She knowingly broke the law with her personal server. Knowingly breaking the law is not the standard here, gross negligence is. And she is guilty of both.
18 U.S. Code § 793
(f) Whoever, being entrusted with or having lawful possession or control of any document, writing, code book, signal book, sketch, photograph, photographic negative, blueprint, plan, map, model, instrument, appliance, note, or information, relating to the national defense, (1) through gross negligence permits the same to be removed from its proper place of custody or delivered to anyone in violation of his trust, or to be lost, stolen, abstracted, or destroyed, or (2) having knowledge that the same has been illegally removed from its proper place of custody or delivered to anyone in violation of its trust, or lost, or stolen, abstracted, or destroyed, and fails to make prompt report of such loss, theft, abstraction, or destruction to his superior officer—
It is not to be anywhere except the government servers that secure it. SIPRNet is the name of the network for transmission of the military information she sent on her private server, to people whom have a need to know.
Former director Comey knew this, and choose to politicize her crime and not prosecute her.