“Pagliano began the migration of the email accounts from the old server to the new one at the house, then finished it up later in his hotel room. When he finished, Pagliano believed he’d “popped out” all of the Clinton staff email from the Apple server; he recalled that he didn’t transfer an email account for Hillary Clinton. The leftover Apple computer, meanwhile, was repurposed as a desktop for the household staff in Chappaqua. On the new system, Pagliano and Cooper both had administrative privileges. A backup system ran once a week.
On March 18, 2009, Hillary Clinton stopped using her longstanding email, hr15@att.blackberry.net, and switched to a new account: hrod17@clintonemail.com. When she switched accounts, all of her old email disappeared—including all of the email from her first seven weeks as secretary of state. To date, neither Clinton nor the FBI have located any of her email from that period.”
https://www.politico.com/magazine/story/2016/09/hillary-clinton-emails-2016-server-state-department-fbi-214307
Older article but clear background info refresher for newfags