Huma Abedin and Cheryl Mills, former Secretary of State Hillary Rodham Clinton’s top aides, used personal email accounts to conduct government business in addition to a State Department email and an account on the controversial server Mrs. Clinton kept at her New York home, the State Department confirmed to a federal court Friday. The State Department admitted to the judge that it doesn’t have control over those documents, and can’t be sure it has all of the records from their time in the administration. John F. Hackett, the top open-records official at the department, said they have officially concluded that...