Dean, declaring how happy he is for the FBI to have Hillary's server, declares also that he's confident she will be vindicated. There's a good summary of the law at the link.
But it doesn't matter. "I don't think she's going to get the blame for it because she didn't know" is a nonstarter as a defense. Given the security markings the Inspector General assigned to the emails, she had to know. You would not have access to sensitive signals intelligence and top-flight imagery without being read into those compartmentalized programs and trained in their Operational Security requirements.
There is no way she or anyone with that access did not realize that what they were doing was a potential violation of security at the highest levels. Long before they sat down to write an email referencing satellite imagery or sensitive signals intelligence, they had been trained to know that before discussing that information they should check its classification level and releasability, and use only appropriate measures. Ignorance of the law is no excuse, but ignorance when you've received extensive and specific training is no excuse at all.