Ars Technica writes Indifference and ignorance: Delving deep into the Clinton e-mail saga
In order to have an intelligent conversation about Clinton’s e-mails, here is a technical analysis of the evidence as it has been presented (think of it like a print version of Congressional hearings, minus screaming, finger-pointing, and grandstanding). A clearer picture has started emerging based on the testimony given by FBI Director James Comey and the Inspectors General of the State Department and the Intelligence Community (OIG), plus a portion of the 30,000-plus e-mails released thus far through FOIA requests by the State Department and other agencies. That picture, based on our assessment, is not a very pretty one."
I basically knew this but it gave a bunch of nice details. If I were to characterize it, corporate (in this case government) IT department didn't keep up technologically with commercial systems and executives (in this case a Secretary) wanted the convenience of commercial systems and did so on their own accord (ignorant of the risks they were taking). Wrong? Yes. Criminal? No, or at least not seriously so. As Comey said, no reasonable prosecutor would charge this, of course we know sometimes prosecutors can be unreasonable, as in the case of Carmen Ortiz prosecuting Aaron Swartz and others.
There's an argument to made here that commercial systems should be made more secure and government IT departments should have more funding to be able to better integrate them into their systems easily.