The only two that I could find are Lisa Jackson, see my note above. And the Ambassador to Kenya, whom Hillary's State Department was fired for using private Email among multiple reasons.
The AP has found that the practice of using private email has exploded in the Obama Administration, including cabinet members like Kathleen Sebelius and Tom Perez.
Top Obama appointees using secret email accounts
Some of President Barack Obama's political appointees are using secret government email accounts to conduct official business, The Associated Press found, a practice that complicates agencies' legal responsibilities to find and turn over emails under public records requests and congressional inquiries.
Finally a recent Wikileaks released email from John Podesta, Hillary Clinton's campaign head, revealed:
A former top Department of State official who worked under Hillary Clinton told her presidential campaign chair every White House staffer and top cabinet official uses a personal email account.
“Btw you know as well as I every god damn cabinet officer and WH staff uses [their] gmail account!” Tom Nides, the former deputy secretary of state for management and resources, wrote to John Podesta in a March 2015 email.