You just are getting. Forget about any emails that were sent to her.
Pretty much every email that Hillary would have type besides get me coffee would have been classified because she was the Secretary of State. She had to mark it. She didn't and moreover she typed emails and sent them through a private server.
Not safeguarding information is illegal. Has nothing to do with markings.
"What matters in the world of secrets is the information itself,
which may or may not be marked “classified.” Employees at the highest levels of access are expected to apply the highest levels of judgment, based on the
standards in Executive Order 13526. The government’s
basic nondisclosure agreement makes clear the rule is “marked or unmarked classified information.”
"The problem for Clinton may be particularly damaging.
Every email sent within the State Department’s own systems contains a classification; an employee technically cannot hit “send” without one being applied. Just because Clinton chose to use her own hardware does not relieve her or her staff of this requirement."
"For example, if an employee were to be handed information sourced from an NSA intercept of a foreign government leader,
somehow not marked as classified, she would be expected to recognize the sensitivity of the material itself and treat it as classified. In other cases, an employee might
hear something sensitive and be expected to treat the information as classified. The emphasis throughout the classification system is not on strict legalities and coded markings, but on judgment. In essence, employees are required to know right from wrong. It is a duty, however subjective in appearance, one takes on in return for a security clearance."