From the FBI's point of view, there would be no intentional misconduct. The actual existence of the server was intentional, but that wasn't illegal.
But, prosecution of mishandling of classified information doesn't require intent. The question is whether it rises to the level of "gross negligence".
The legal definition of gross negligence is "a conscious and voluntary disregard of the need to use reasonable care, which is likely to cause foreseeable grave injury or harm to persons, property, or both."
I think that Clinton's behavior meets that standard, along with every single person that sent email to her on that server.
So that means ANYBODY can do it! We are so doomed as a country.