The State Department found 30 instances of mishandling of classified information by 15 people related to former Secretary of State Hillary Clinton's private, unsecure email system.
The Washington Times reported the department said in a letter to Sen. Chuck Grassley, R-Iowa, that 15 people "got write-ups" placed in their security files over the issue.
The notations "could affect future attempts to gain security clearances," the paper said.
The full review of the matter is not completed, but so far 23 violations and seven infractions of security protocols related to Clinton's email scandal have been found.
Mary Elizabeth Taylor, an assistant secretary for legislative affairs, told the Times such violations are "a serious matter."
Clinton violated State Department rules by setting by setting up her own server and clintonemail.com address to transmit government-related messages, including classified information.
"But Mrs. Clinton was too ignorant of the risks to be able to be charged, former FBI Director James B. Comey concluded in 2016 – a decision the Obama Justice Department quickly ratified, amid the presidential election," the report said.
Taylor said more information will be released when the department review is finished.
So far, investigations have found that more than 2,000 emails contained classified information.
About two dozen emails contained top secret information.
Officials did not release the names of employees who broke rules.