We need to know the truth
I have a mail server. If someone sends me a beyond top secret copy of Thursday's lunch menu (to paraphrase an earlier poster) is it my fault? Theoretically, my entire server then becomes beyond top secret, including everything already on it, and thus has to be destroyed in a controlled thermonuclear detonation.
The key questions are:
a) was she *sending* classified emails from it?
b) was she aware that she'd received classified emails on her server, in which case, why didn't she do something about it?
c) WhyTF was she doing "work stuff" on her own server?
Either way, the full weight of American justice should be brought to bear, and she should spend the next 10 years on death row, at least.