She had been asked to give sworn responses to 25 written questions from a conservative legal group.
At least 21 responses used variations of "does not recall", the documents, provided by her lawyer, show.
Mrs Clinton denies handling classified information in her private emails.
Questions over her use of a private email server while secretary of state have dogged her presidential campaign.
Her responses under oath to the Judicial Watch group were provided by her lawyer, David Kendall.