When Clinton became secretary of state in January 2009, her emails were hosted on her first private email server, which was an Apple computer (either an Apple Power Macintosh G4 or G5 tower). In March 2009, the server was replaced by a new one built by Clinton’s computer technician Bryan Pagliano. The old server was repurposed to serve as a personal computer and/or workstation for household staff at Clinton’s Chappaqua, New York, house.
At some unknown point in 2014, the data on this Apple computer is transferred to an Apple iMac computer. The hard drive of the old Apple computer is then discarded. Clinton’s emails from January 2009 until around March 18, 2009, are apparently lost as a result.
On October 14, 2015, Williams & Connolly, the law firm of Clinton’s personal lawyer David Kendall, tells the Justice Department that a review of the iMac was conducted, as requested by the Justice Department, and no emails were found belonging to Clinton from when she was secretary of state. The FBI will not directly examine the iMac. (Federal Bureau of Investigation, 9/2/2016)