The emails are under investigation, and one intelligence source said it was still unclear who was behind them.

Another government source said that U.S. officials are investigating whether people in Iran had hacked into a Proud Boys network or website to distribute threatening materials. This source said U.S. officials suspect the Iranian government was involved but that the evidence remains inconclusive.

Some of those emails also contained a video, debunked by experts, that purported to show how fake ballots could be submitted. Ratcliffe said that claim was false.