The issue ScienceDuck is that by using her own email server to store her emails (which no one else has ever done, despite the misstatement by Wills to the contrary), Clinton gave herself complete and sole control and access to her email archive, even though it was being used for official government business.  The difference between Clinton and Rice or Powell is that they also had government email accounts, which they primarily used for their official business.  Clinton, however, NEVER had a govt account.  ALL of her email went through her own private server

If she had used a govt account, like Rice and Powell, then the government would have access to the server containing the emails.  And if you use a commercial email service like Hotmail, as an example, Microsoft controls and has access to the server that the email resides on.

Clinton basically stored her emails where no one else would have access to them, even though she was conducting government business.   How convenient is that?