Witnesses testified about missing e-mails and mismanagement of subpoenaed White House records. Northrup Grumman employees who operated the White House e-mail system said that thousands of e-mails had not been archived as mandated by federal law and that relevant e-mails had not been provided for several investigations due to a server error. They also answered questions about potential obstruction of justice by White House officials for trying to conceal the problem.