It is a false claim that the information was "retroactively classified". It was classified at the time of sending and receiving. There was information that is always classified highly, information about methods and sources. Even Hillary does not make that claim that it was "retroactively classified" anymore. She says it was not marked at the time, which is a meaningless distinction. Classified information is about what the information is about not the markings. A number of people have been sentenced for information that was not marked. Leaking the name of Valerie Plame a CIA agent led to a long investigation with Scooter Libby going to prison. This information was not marked. David Petraeus was disgraced and sentenced to two years probation and fined $100,000 for having person journals of his time serving this country and sharing them with his biographer. I doubt his personal journals contained security markings. Many people thought he got off too easy. In summary, if Hillary was a regular person she would most likely be going to prison.