At a Congressional hearing, FBI Director James Comey is asked by Representative Trey Gowdy (R), “Secretary Clinton said there was nothing marked classified on her emails, either sent or received. Was that true?”
Comey replies, “That’s not true. There were a small number of portion markings on, I think, three of the documents.” Later in the day, the State Department says that two of those emails were incorrectly marked as classified when they were sent. Both of those emails, sent on April 8, 2012 and August 2, 2012, were released as part of the over 30,000 emails Clinton made public. It is unknown which email Comey is referring to in the third instance. It could be the part marked classified is redacted, or perhaps the email has not yet been released. (Politico, 7/7/2016) (CNN, 7/7/2016)
A September 2016 FBI report will give more information on these emails, including mentioning that the third email is still classified at the “confidential” level.