Fred Kaplan in The Atlantic, puts it in some context, Hillary’s email scandal was overhyped.
Top secret information is another matter, but the stuff that showed up in Clinton’s private email wasn’t so special. Seven of the eight email chains dealt with CIA drone strikes, which are classified top secret/special access program—unlike Defense Department drone strikes, which are unclassified. The difference is that CIA drones hit targets in countries, like Pakistan and Yemen, where we are not officially at war; they are part of covert operations. (Defense Department drone strikes are in places where we are officially at war.) But these operations are covert mainly to provide cover for the Pakistani and Yemeni governments, so they don’t have to admit they’re cooperating with America. Everyone in the world knows about these strikes; nongovernment organizations, such as New America, tabulate them; newspapers around the world—including the New York Times, where some of the same reporters are now writing so breathlessly about Clinton’s careless handling of classified information—cover these strikes routinely.
The other top secret email chain described a conversation with the president of Malawi. Conversations with foreign leaders are inherently classified.
In other words, even if Russian, Chinese, Iranian, or Syrian spies had hacked into Clinton’s email servers, and if they’d pored through 60,000 emails and come across these eight chains that held top secret material, they would not have learned anything the slightest bit new or worthy of their efforts. The FBI’s discoveries should be viewed in that context."
There are a few federal statutes dealing with the mishandling of classified information. Some are defined as misdemeanors, some as felonies. But all of them require the finding of an “intent” to mishandle information—and most of them involve an intent to share the information with people (usually, but not always, foreign agents) who are not cleared to see it. As Comey said of the Clinton case, “We do not see these things here.”
He goes on in the comparisons to Petraeus, to lower ranked officials, to her use of multiple devices, to leakers and more.
Kevin Drum points out, Hillary Clinton Never Came Close to Compromising National Security.
If you choose to believe that top secret is top secret, and it doesn't matter if the classification was ridiculous, that's fine. Knock yourself out. The rest of us can examine Emailgate in a real-world sense and try to decide if Hillary Clinton actually did anything that might have compromised national security. The answer, pretty clearly, is no. We've seen virtually all the emails. We know what the top secret emails were about. We know that Russia could have hacked into her server and read every word and learned nothing of interest.
Hillary was still careless, and she still shouldn't have done it. But for anyone interested in actual national security, it's pretty clear that she never came close to compromising anything even remotely important. We've known this for many months. We still know it. And all the faux outrage from Republicans in Congress won't change it.
If you want more, factcheck.org goes into some gorey details, Revisiting Clinton and Classified Information.