In June 2013, Platte River Networks (PRN) takes over management of Clinton’s server. Late in the month, they replace the server with a new one and then transfer the data to it. They subcontract with the company Datto, Inc. and purchase a device called the Datto SIRIS S2000 to make periodic back-ups of all the data on the new server. The first such back-up takes place on June 24, 2013.
But data is still being transferred from the old server to the new one. The June 29, 2013 back-up will later prove to be the most important one for FBI investigators, as it apparently is the first one after the data transfer is completed. From that point onwards, emails from Clinton’s four years as secretary of state are likely to only get lost from the server, not added.
The FBI will later report that all of Clinton’s emails at the start of Clinton’s tenure as secretary of state, from January 23, 2009 to March 17, 2009 were missing from the over 30,000 emails Clinton handed over. But the FBI’s Clinton investigation recovered some these emails because they were “captured through a Datto backup on June 29, 2013. However, the emails obtained are likely only a subset of the emails sent or received by Clinton during this time period.”
Clinton’s first server was replaced around March 18, 2009 by the same server that PRN then decided to replace in June 2013. But presumably some of the emails on the first server were transferred to the second server, from instance by being in email inboxes, and then were transferred again by PRN to the newest (and third) server.
One thing that isn’t clear is how many of the emails from after March 18, 2009 were recovered by the FBI. It also isn’t clear if the FBI recovered emails from a Datto device attached to the new server, or if it was from a copy of the data that Datto kept in the “cloud,” over the Internet. (Federal Bureau of Investigation, 9/2/2016)