The end of the FBI's year-long investigation comes just weeks before the Democratic convention, during which Clinton is expected to become the party's nominee for president.
But even as Comey said the FBI wouldn't recommend charges -- the final decision will be made by the Department of Justice -- he also delivered a scathing verbal indictment of her behavior. Here are seven quotes from Comey on an issue that is sure to reverberate into the fall campaign:
"Although we did not find clear evidence that Secretary Clinton or her colleagues intended to violate laws governing the handling of classified information, there is evidence that they were extremely careless in their handling of very sensitive, highly classified information."
2. "Should have known"
"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 those matters, should have known that an unclassified system was no place for that conversation."
3. "Especially concerning"
"None of these emails should have been on any kind of unclassified system, but their presence is especially concerning because all of these emails were housed on unclassified personal servers not even supported by full-time security staff, like those found at agencies and departments of the United States government -- or even with a commercial email service like Gmail."
4. "Still obligated to protect it"
"Only a very small number of the emails containing classified information bore markings indicating the presence of classified information. But even if information is not marked 'classified' in an email, participants who know or should know that the subject matter is classified are still obligated to protect it."
5. "Generally lacking"
While not the focus of our investigation, we also developed evidence that the security culture of the State Department in general, and with respect to use of unclassified email systems in particular, was generally lacking in the kind of care for classified information that is found elsewhere in the government.
6. "Hostile actors"
"We do assess that hostile actors gained access to the private commercial email accounts of people with whom Secretary Clinton was in regular contact from her personal account. We also assess that Secretary Clinton's use of a personal email domain was both known by a large number of people and readily apparent."
7. "Sophisticated adversaries"
"She also used her personal email extensively while outside the United States, including sending and receiving work-related emails in the territory of sophisticated adversaries. Given that combination of factors, we assess it is possible that hostile actors gained access to Secretary Clinton's personal email account."