Originals here:
https://archive.org/details/ARRBmailsAndHardDrives but are zipped and in different file formats. These have been unzipped and turned into pdfs. This makes them searchable in archive.org.
The Assassination Records Review Board was an independent agency formed to re-examine for release the assassination-related records that federal agencies still regarded as too sensitive to open to the public. This release consists of 52,387 ARRB emails and 16,627 files from the ARRB drives.