Yes, you can scan that many emails in a short time

Wired - The FBI can review hundreds of thousands of emails in a week, using automated search and filtering tools rather than Lynn’s absurd notion of Comey reading the documents manually. “This is not rocket science,” says Jonathan Zdziarski, a forensics expert who’s consulted for law enforcement and worked as a systems administrator. “Eight days is more than enough time to pull this off in a responsible way.”

One former FBI forensics expert even tells WIRED he’s personally assessed far larger collections of data, far faster. “You can triage a dataset like this in a much shorter amount of time,” says the former agent, who asked to remain anonymous to avoid any political backlash. “We’d routinely collect terabytes of data in a search. I’d know what was important before I left the guy’s house.”