Comment by GVIrish

Right, but State Department has Classnet for classified materials, this is not a case of Clinton plugging into Classnet with a private server.

The fact that other people sent information to her Opennet email address that contained information derived from classified documents is not necessarily damning for Clinton. If someone from DoD or any of the intelligence agencies pulled information from a classified document and sent it to a public email address, that spillage would be on the sender.

If Clinton realized that classified info came into her inbox then she would be responsible for getting that information off an unclassified machine. But if someone pasted an excerpt from a classified source into an unclassified email, the recipient of that email may not know that it was in fact classified information. Certain types of information should ring alarm bells for the recipient, but the classification of other types of information are not always going to be apparent if the information is not marked (secret, top secret, sbu, etc).

To date there doesn't seem to be anyone claiming there was intentional spillage on Clinton's part, or that she personally took classified information and put it on an unclassified system. There may yet be more revealed but right now it doesn't look like she did anything meriting prosecution.