Hillary Clinton did not mention the FBI's decision to review additional emails related to its investigation into her private server during a rally in Iowa on Friday.
The Democratic nominee has yet to comment on FBI Director James Comey's letter to the Senate Judiciary Committee revealing the discovery of more emails related to the investigation into Clinton's use of a private email server while secretary of state.
A senior law enforcement official told NBC News the letter was sent to lawmakers "out of an abundance of caution" and to be extra-thorough.
The official said the emails were discovered "on another device" during a different investigation.
At a rally earlier in the day, Donald Trump commended the FBI for having "the courage to right the horrible mistake they made" earlier in the summer.
Comey announced in July that the FBI would recommend not pressing criminal charges against Clinton for her email use while serving as secretary of state.
Update: Following the rally, Clinton campaign chair John Podesta released a statement saying Comey "owes it to the American people to immediately provide the full details of what he is now examining. We are confident this will not produce any conclusions different from the one the FBI reached in July."