 -- The State Department published more than 7,000 pages of emails from former Secretary of State Hillary Clinton's private account to its public records website Monday evening.

It's the fourth and largest installment of emails, most of which were sent or received within the years 2009 and 2010. The State Department has now released just over 25 percent of the total amount of her emails in its possession. The agency hopes to have all her emails released by the end of January 2016.

Clinton, the front-runner for the Democratic presidential nomination, maintains she did not handle classified material on that account.

Yet among the emails released tonight, 125 were deemed classified by the State Department after the fact in order to shield them from public view.

Those emails were not marked classified at the time they were sent or received on Clinton's server, but following a review for public release the State Department determined those emails needed to be upgraded to a "confidential" status, one of the lowest levels of classification.

As a result the 125 emails were heavily redacted before they were published on the State Department's website and marked 'B1', which refers to a Freedom of Information Act (FOIA) exemption code. That code states that anything determined to contain "classified information for national defense or foreign policy" is exempt from public release.

So far about 188 of Clinton's emails have been determined to be "classified" documents.

Clinton had often said that she never handled anything "marked" classified at the time it was originally sent or received. That statement appears to be true. But it's not possible to send a properly marked and classified email through an unclassified State Department account or a private email account, according to multiple senior government officials familiar with handling sensitive materials in the government email system.

It is possible, however, to quote from a classified email and send that through an unclassified system, which unless reported by the sender or receiver would not be detected until a later review.

One email released tonight demonstrates that at least one member of the State Department’s “Help Desk” was unaware that Secretary Clinton was using a private email address.

On Saturday, February 27, 2010 a help desk analyst named Christopher Butzgy sent an email to HDR22@clintonemail.com, unaware that he was communicating with the Secretary of State. He informed her that one of his customers had been “receiving permanent fatal errors from this address.”

Secretary Clinton forwarded the email to her aide and advisor Huma Abedin asking, “Do you know what this is about?”

“Ur email must be back up!!,” Huma replied, before explaining that the error messages prompted a staffer to get State Department Help Desk involved. “They had no idea it was YOU, just some random address so they emailed,” Abedin wrote.

Republican front-runner Donald Trump has repeatedly compared Clinton's email scandal to that of retired CIA Director, Gen. David Petraeus, who earlier this year plead guilty to a misdemeanor charge of mishandling classified information. He was originally charged with a felony, but pleaded guilty to a lesser charge in a deal with the prosecution.

One of those prosecutors penned a story in USA Today Sunday evening, claiming that Trump is making a false comparison. Anne Tompkin describes herself as the former US attorney for the Western district of North Carolina and said she oversaw the prosecution. "The key element that distinguishes Secretary Clinton’s email retention practices from Petraeus’ sharing of classified information is that Petraeus knowingly engaged in unlawful conduct, and that was the basis of his criminal liability," Tompkin wrote. The USA Today also noted that Tompkin has donated to Clinton's presidential campaign.