“In a letter to Congress, the F.B.I. director, James B. Comey, said that emails had surfaced in an unrelated case, and that they ‘appear to be pertinent to the investigation.’

Mr. Comey said the F.B.I. was taking steps to ‘determine whether they contain classified information, as well as to assess their importance to our investigation.’ He said he did not know how long it would take to review the emails, or whether the new information was significant.”