Nonsense, Mr/s Clinton apologist. Well before that law was passed, there was already a requirement to retain all official communications, including emails. She set this up specifically to get around such scrutiny, and did it the moment that she was named as the nominee for the job. Her use of a false name on the registration and cash payment to the consultant just contributes to the atmosphere (and reality) of deliberate avoidance of the legal requirements.
A law the speaks directly to the matter of forwarding along private messages from private mailboxes that get occasionally used in connection with official duties doesn't mean that the already existing laws about retaining all official communication didn't already exist. They did. She chose not to establish an official mailbox at State. Her personal mail account on her phony-name-registered domain WAS BY DEFAULT her official email channel. And she did not in any way comply with the existing laws that required ongoing official storage of her communications within government systems and available for things like FOIA requests. Countless FOIA requests for her correspondence were in fact completely ignored because of this deliberate loophole that she established (look! no official records of my communication exist because there are no records!).
And because it's her own private email sandbox, SHE gets to decide which messages she should or shouldn't pass along for official archiving per the law. We as her employers have no recourse to see if her judgement on the matter is or was sound, or even legally correct. This was a deliberate act on her part to avoid legally mandated scrutiny of her communications as a government official. Combine that with her panhandling for donations from foreign governments (WHILE she was Secretary of State!) to fund the foundations from which her family drew income and which did things like fly them around the world in luxury accommodations, and you can see why she might indeed want to dodge the law and hide her communications.