Federal and legal experts are questioning Clinton's use of personal email accounts for government business, since her habit of doing so was reported by the New York Times on Monday.
The White House said Tuesday Clinton appeared to have violated "very specific guidance" from the president that members of his administration should use government email accounts for all official business.
Clinton's use of non-government email could have violated the Federal Records Act. The State Department has said there's no indication Clinton used her personal email to deal with classified information.