Hillary Clinton wrote 104 emails that she sent using her private server while secretary of state that the government has since said contain classified information, according to a new Washington Post analysis of Clinton’s publicly released correspondence.

The finding is the first accounting of the Democratic presidential front-runner’s personal role in placing information now considered sensitive into insecure email during her State Department tenure. Clinton’s authorship of dozens of emails now considered classified could complicate her efforts to argue that she never put government secrets at risk.

Clinton sometimes initiated the conversations. More often, she was replying to aides or other officials with brief reactions to ongoing discussions.

The analysis also showed that the practice of using non-secure email systems to send sensitive information was widespread at the department and elsewhere in government.

Clinton’s publicly released correspondence also includes classified emails written by about 300 other people inside and outside the government, the analysis by The Post found. The senders included longtime diplomats, top administration officials and foreigners who held no U.S. security clearance.

In those cases, Clinton was typically not among the initial recipients of the classified emails, which were included in back-and-forth exchanges between lower-level diplomats and other officials and arrived in her inbox only after they were forwarded to her by a close aide.

For federal employees other than Clinton, nearly all of the sensitive email was sent using their less secure, day-to-day government accounts. Classified information is supposed to be exchanged only over a separate, more secure network.

The Post analysis is based on an examination of the 2,093 chains of Clinton’s email correspondence that the State Department decided contained classified information. The agency released 52,000 pages of Clinton’s emails as part of a court-ordered process but blocked the sensitive information from public view. The Post identified the author of each email that contained such redactions.

The analysis raises difficult questions about how the government treats sensitive information. It suggests that either material is being overclassified, as Clinton and her allies have charged, or that classified material is being handled improperly with regularity by government officials at all levels – or some combination of the two.

The analysis did not account for 22 emails that the State Department has withheld entirely from public release because they are “top secret,” the highest level of classification.

The handling of those emails has drawn particular criticism from Republican lawmakers and officials in the intelligence community, who have argued that Clinton’s use of a private server exposed some of the government’s most closely guarded secrets to hacking or other potential breaches.

The FBI is investigating the security of the server and whether Clinton or her aides mishandled classified information.

Clinton spokesman Brian Fallon said the large number of people who sent and received emails that were declared classified was a sign of “overclassification run amok, and indicates that our system for determining what ought to be classified is broken.”