[Qiviut]

Not only ‘voluntary’, but she was ‘pleased’ ..... per Clinton campaign spokesman Nick Merrill:

“She is pleased to have had the opportunity to assist the Department of Justice in bringing this review to a conclusion. Out of respect for the investigative process, she will not comment further on her interview.”

[daler]

Or, put another way by PBS:

"Isn't she wonderful?"

[submarinerswife]

“She is pleased to have had the opportunity to assist the Department of Justice in bringing this review to a conclusion”

Then she should do everything to stop the State Dept from asking a judge to seal the Clinton foundation records for 27 months.