Hillary Clinton’s presidential campaign chairman offered a new explanation in a recent memo to big-dollar donors for why the Democratic front-runner used a private email system.

“Had Secretary Clinton known of any concerns about her email setup at the time, she would have taken steps to address them. She believed she was following the practices of other Secretaries and senior officials,” John Podesta wrote in a memo obtained by Buzzfeed.

[dcquiz] The letter comes in the wake of a damning report from the State Department’s inspector general which found that Clinton violated agency policy as secretary of state by using an off-the-books email system, which consisted of a personal email account and home-brew server.

Clinton did not inform State Department officials about the system, though the watchdog’s report said she had an “obligation” to do so. She also failed to follow State Department policy by failing to tell State Department information security officials about two attempted hacking attempts on the server, which was managed in secret by State Department information technology specialist Bryan Pagliano.

In the memo, Podesta wrote that Clinton’s use of the server was “a mistake,” something that the former secretary of state has acknowledged as well.

But the campaign official’s new claim that the email setup was in keeping with her predecessors — Colin Powell and Condoleezza Rice — highlights Clinton’s shifting explanations about the system .

In the months since the email scandal broke open, Clinton has pointed to reports about Powell’s use of a personal email account while in office. She has also said that she used the same server that was used by former Bill Clinton’s office and she used only one non-government email account — which was routed through her personal BlackBerry — “for convenience.” Neither she nor her campaign has claimed, until Podesta’s letter, that she thought that her email setup was carrying on in the tradition of her predecessors.

She has also never suggested that she reached out to Powell or Rice to find out about their email arrangements. Had she done so, she likely would have learned that neither of them used a private email server.

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