These articles are always written by people with neither a legal background, nor any experience in dealing with classified materials.
That she was careless is almost a given, which is kinda strange considering how paranoid she can be. Her tendencies would have gotten her chastised if she hadn't been Sec. State. But since she wasn't, little will come of it now. There is little if anything here that anyone is going to try to prosecute. Her lawyers can dig up just enough evidence to establish that some people would not have classified the information in that context. Right, wrong or indifferent, that makes for an extremely weak case, especially in the context of a trial which would immediately be characterized as a political witch hunt.
And even if she had tried diligently, I can tell you right now, she would have failed to never have sent/forwarded/received emails that contained classified information. And her lawyers would have little trouble establishing this by the most cursory review of existing State Department emails. They could pick almost any high official and find just enough mistakes to establish that this happens.
Now, if she can't establish that she actually had "approval" from some place to use her privately held server for official business, THEN she'd be in some trouble. But no one has tried to suggest that. So that's her "get out of jail free" card. She never should have been given approval because of EXACTLY what they are now finding. And that doesn't even address the records retention part of all of this, which ALSO should have prevented her from using a private email server. And this all should have been well known considering how much trouble the Bush administration got into for using the GOP email system. But none the less, she apparently got the approval to use the private system and so she's covered.
I know, the FBI and immunity and all of that. I also remember how Rove was going to be "frogged marched" right out of the White House because of a lot worse stuff. There is nothing here except the political circus and the wishes of those who'd like to see her take a fall.