It also means they should have logs of those emails, showing at least the timestamp, sender, recipient, and subject.
If they have lots of the emails it would be interesting to see for her trip to Libya when she mysteriously sent -0- emails
Intel (MacAfee's parent company) is a big DoD, NSA and other Federal agencies contractor.
Congressional oversight committees could easily demand those records, under penalty of disbarment from all Federal contracts, even if DoJ won't touch it. They'll cave after putting up a show of resistance (as they surely donated millions to Clinton Foundation and Clinton campaigns.)