In a September 2016 report, the FBI will reveal that the “FBI forensically identified deletions from [Clinton’s] server on March 8, 2015 of .pst files not associated with Clinton’ s email account or domain, and other server data.”
A .pst or “Personal Storage Table” file is a file format used to store copies of emails and other items within Microsoft software.
This incident will only be mentioned in a footnote in an FBI report, with no mention of who made the deletions or why. It also is not clear how thorough the deletions are. Clinton’s deputy chief of staff Huma Abedin had a frequently used email account hosted on the server, but it is unknown if these deletions include her emails.
It seems probable an employee of Platte River Networks (PRN), the computer company managing Clinton’s server, made the deletions. Shortly after a news report made Clinton’s use of the server public knowledge on March 2, 2015, Cheryl Mills, who is one of Clinton’s lawyers as well as her former chief of staff, requested that PRN conduct a complete inventory of all equipment related to the server, and one unnamed PRN employee physically checked the server while another one remotely logged on to check it.
The FBI report will also mention that around March 7, 2015, PRN makes various changes to the server’s security settings. (Federal Bureau of Investigation, 9/2/2016)