Although I’m reluctant to offer a ThinkProgress.com piece as an example of fair-minded journalism (it’s a great source, just one with an avowed viewpoint as reflected in its title), but this article strikes a pretty good balance between providing context about the investigation into HRC’s email while at the State Department and getting into the tall grass.
You may not conclude that there’s not a criminal case here, but at least be armed with the specific facts, law, and history.