Hillary Clinton has said her family paid a State Department employee to maintain the private email server she used while secretary of state.
She said Bryan Pagliano continued to receive payment for his technical service “for a period of time”.
Mr Pagliano has told a House committee investigating Mrs Clinton’s use of the email server that he would invoke his Fifth Amendment right against self-incrimination if called to testify.
The Democratic front-runner for president addressed the email issue when she spoke to reporters after a campaign evening in Portsmouth, New Hampshire.
Mrs Clinton said “we obviously paid for those services and did so because during a period of time we continued to need his technical assistance.”
She said she set up her own system because of the convenience of using a single hand-held device.