It's not just Hillary.
Former New York City Mayor Mike Bloomberg used a private email server almost exclusively to send work related emails, the New York Daily News reports.
As a result, "not a single email sent by Bloomberg during his tenure has been made available for public inspection," the News says.
Bloomberg is not accused of any wrongdoing for using his Bloomberg.net email for his entire, three-term tenure. And his predecessor, Rudy Giuliani, moved his correspondence to a private nonprofit out of public view; they were later made public after municipal outcry.
"The City Charter makes explicitly clear that outgoing administrations are required to provide records of 'historical, cultural or other important value' to the archives," Bloomberg rep Marc LaVorgna told the News. "We fully complied with that program and had the most aggressive and expansive records retention program in the city's history."
Hillary Clinton's use of a private email server while serving as U.S. Secretary of State remains the subject of an ongoing investigation. But ABC News legal analyst Dan Abrams has argued she is unlikely to be charged with any crime, since at the time it was not illegal for her to use such a server. It's also not clear whether she knowingly transmitted any classified material.
But the News interviewed legendary historian Robert Caro to capture the frustration of not being able to access work-related emails.
"It would be a huge problem for historians trying to write a history of the Bloomberg era—and it is an era in which he as mayor did so much to shape the future city," Caro said.
Rob covers business, economics and the environment for Fusion. He previously worked at Business Insider. He grew up in Chicago.