Mostly True
"Classified material has a header which says ‘top-secret, secret, confidential.’ Nothing, and I will repeat this and this is verified in the report by the Department of Justice, none of the emails sent or received by me had such a header."

Hillary Clinton on Wednesday, September 7th, 2016 in the NBC Commander-In-Chief Forum

Hillary Clinton says none of her emails had classification headers

Hillary Clinton speaks at a forum on national security and veterans' issues hosted by MSNBC's Matt Lauer at the Intrepid Sea, Air & Space Museum in New York. (New York Times)

During an NBC forum that focused on the presidential candidates’ national security chops, host Matt Lauer asked Democratic nominee Hillary Clinton why it isn’t disqualifying that she dealt with highly sensitive material on a private, unclassified email system.

Clinton said she made a mistake using the system, but she still took classification seriously.

"I have a lot of experience dealing with classified material, starting when I was on the Senate Armed Services Committee going into the four years as secretary of state," she said. "Classified material has a header which says ‘top secret, secret, confidential.’ Nothing, and I will repeat this, and this is verified in the report by the Department of Justice, none of the emails sent or received by me had such a header."

Given that we’ve found Clinton’s email did contain some classified information, this statement intrigued us.

Information isn’t classified until a designated authority within the government declares it classified. The way that person shows their determination is by adding a header and footer to the relevant document, often tacking on a cover sheet, too — all to make it clear that the document contains classified information.

Clinton is correct that the FBI did not find any such labels in her emails.

Of the tens of thousands of emails the FBI reviewed, 81 email chains found on Clinton’s private servers included classified information, as determined by various U.S. intelligence agencies, according to a FBI report released Sept. 2. Just three email chains included some sort of classification marking: At least one paragraph preceded by the marking "(C)," indicating that those paragraphs were "confidential," the lowest level of classification. But none of the three had a header, footer or cover page further signaling that the emails contained confidential information.

Even though there was a "(C)" preceding the paragraphs, this information was not properly marked confidential because it did not include the header, FBI Director James Comey said in a July 7 hearing before Congress. It’s "reasonable," he said, that Clinton may not have realized these were classified.

For Clinton’s part, she told the FBI that "she did not know what the "(C)" meant at the beginning of the paragraphs and speculated it was referencing paragraphs marked in alphabetical order," according to the bureau’s report. She also disputed the need for these particular paragraphs to be classified at all.

So that’s three email chains out of 81 found to include classified information on Clinton’s private email server. What about the other 78?

Clinton, in her statement, said classified material has a header that says "classified" and that none her emails had that header. But that leaves out the possibility of what happened in this case — classified information is left unlabeled as a result of human error.

All information determined to be classified should have a header in order to designate it properly. But if someone makes a mistake and forgets to include the label after that original determination, the information is still classified.

"In that case, the information was classified, but in the absence of markings, the person receiving the information may have no realistic way of knowing that fact," said Liza Goitein, co-director of the liberty and national security program at the Brennan Center for Justice.

" ‘Classified’ isn’t an inherent or self-evident status. It’s an act," she said. "And that act is rather meaningless if not conveyed to others."

Comey has said it’s understandable that Clinton did not realize some of this unmarked information was classified. But he also has said she should have recognized by the topic of discussion that some of these emails did not belong on a non-classified system, given that 36 of these email chains had "secret" information and eight had "top secret" information.

"There is evidence to support a conclusion that any reasonable person in Secretary Clinton's position or in the position of those with whom she was corresponding about the matters should have known that an unclassified system was no place for that conversation," Comey said in a July 5 statement.

For example, some of these email discussions touched on the CIA’s drone program. Members of Clinton’s staff told the FBI that some of this supposedly classified drone-related information had already been revealed to the public in news reports.

Clinton regularly dealt with classified information as secretary of state. She has said she viewed classified information in hard copy in her office, and she used other secure channels when traveling. Some emails now made public actually show Clinton’s team discussing how they couldn’t email each other classified information over the private server and instead had to move the conversation to a more appropriate venue.

In the end, Comey said the Justice Department shouldn’t prosecute Clinton because there isn’t enough evidence that she intentionally mishandled classified information, nor did investigators find vast quantities of exposed classified material.

Many transparency experts say the government regularly over-classifies, such as classifying information that wouldn’t actually damage national security if released. That’s likely the case regarding Clinton’s emails, said Thomas Blanton, director of the National Security Archive at George Washington University, which favors less classification.

"The point is there's no objective standard for classification," Blanton said. "Very little of what's classified would be deemed so by all experienced observers."

Our ruling

Clinton said, "Classified material has a header which says ‘top secret, secret, confidential.’ Nothing, and I will repeat this, and this is verified in the reports by the Department of Justice, none of the emails sent or received by me had such a header."

For information to be considered properly marked classified, it must contain a header. Clinton is correct that nothing in her email had a header signifying its classification status. Three email chains had a "(C)" indicating "confidential" information, but that is not enough to consider the emails properly marked classified.

But that doesn’t mean there wasn’t any classified information in her email. If someone has determined information to be classified, it is still technically classified even if someone neglects to label it down the line. The FBI found 81 email chains that contained information determined to be classified, though none of the information was appropriately labeled, so it wasn’t necessarily obvious to the recipients.

Clinton’s carefully worded statement is accurate but needs additional information. For that, we rate her claim Mostly True.

Editor's note: The original version of this fact-check ended with the definition of Half True. The fact-check has been revised to include the definition of Mostly True.