Edited the timestamp.
You can go in to a specific text stream and change times/dates but then it becomes just a text in essence. If this is what they are providing, then it is meaningless.
You can reset your computer clock and it will do all the resetting of any new emails with the old date, but when ‘sent’ anywhere that are overhead handshakes between the servers that process the transmission are not changed.
It would be difficult to make it completely chronologically pure as that would require resetting all the servers that touch it along the way. If they are asked to show this ‘trail’ my guess is that they will stonewall this harder than this hard drive crash crap, because if they are caught screwing with the entire system that way, that smacks of just plain old treason.