The announcement may not sway many opinions before the November 8th vote. Many people are either convinced that Clinton's private server was an unforgivable breach of national security, or else see it as a mistake that Clinton has learned from in the years since leaving office.

However, the findings will have a very practical effect on Clinton. Whatever the outcome of the election, she won't have to worry about the new emails leading to legal action. However, they may raise scrutiny of the FBI. Why talk about investigating new messages when it was only going to take days to decide whether or not they were relevant? The Guardian's sources claim that the FBI disclosure was an intentional leak by FBI staffers bent on taking down Clinton, and those concerns (merited or not) are only going to grow now that the investigation has proved fruitless.