The law doesn't require intent.
But, it's hard to say there was no intent on SOMEONE's part, when email was sent to Clinton on her private server with the classification header still intact.
https://fnn.app.box.com/s/7hako8mparyxptisygd1f5wcmwgjnzup
Look for the (C) near the bottom of the first page.
If the email headers are correct, Monica Hanley sent the original message via the public Internet, from an insecure State system to Clinton's server. Then, Clinton replied to the message, leaving the body intact. So, it made ANOTHER trip over the public Internet from one insecure server to another.
How do you discipline an ex-employee?
I worked 28 years for the State Department. There are two distinct email systems, one for classified information and one for unclassified. How did the classified information migrate from one system to another. There had to be intent to circumvent the classification system.