The comments stoked speculation about a possible ongoing probe connected to the charitable organization, even after the Justice Department on Wednesday abandoned the possibility of charges against Clinton, now the presumptive Democratic presidential nominee, for mishandling classified information.
Spokesman John Kirby said the emails probe is restarting now that the Justice Department is not pursuing a criminal prosecution.
"We will aim to be as expeditious as possible, but we will not put artificial deadlines on the process", said State Department spokesperson Jack Kirby.
News about the FBI investigation led to "Clinton" being the top trending item on Twitter this afternoon, with more than 610,000 tweets using that hashtag. No end date has been set for the review, which Kirby explained could result in "administrative sanctions" against State Department officials involved in any wrongdoing.
"I see evidence of great carelessness", he said.
A number of prominent Republican lawmakers, including House Speaker Paul Ryan, argue the handling of the private email server, which Mr. Comey had called "careless", should bar Clinton and her staff from receiving classified intelligence briefings. It had initiated the review back in January, after 22 emails were declared top secret, but was halted when the FBI began its own investigation, according to Fox. Options range from counselling and warnings, to the revocation of an individual's security clearance.
But Comey also said "no reasonable prosecutor" would bring a case against Clinton, and Attorney General Loretta Lynch said she would not bring charges against the former first lady. "I am certainly relieved and glad that the investigation has concluded but I also know how important it is to make sure everybody understands that I would certainly not do that again", Clinton said.
Reports are coming out that the Federal Bureau of Investigation states some of the classified information was allowed to be accessed by Clinton aides that did not have clearance. "There's no question she violated policy", Lankford said.
The chairman of the House Government and Oversight Committee, Republican congressman Jason Chaffetz of Utah, said he would refer Mrs Clinton's testimony to the FBI to investigate whether she lied to Congress.
Clinton's use of an unsecured, private email server was anything but a conscious effort to skirt public reporting requirements, Lucas said.