I've seen no evidence whatsoever that she was the one emailing about this. Rather some of her subordinates did and forwarded some of the messages to her. Which they shouldn't have done even if she had a state.gov email.
No matter how badly the Republicans (or Bernie Bros) want it to be, she isn't a criminal just because some of her employees sent her some email containing classified info. If anything, they are the ones who committed the crime, though it is doubtful any of them will be indicted either.