I've had several requests in the past to spy , gather files, record plaintext conversations over the network and even managerial requests to plant porn on certain employee laptops as to make a firing process go allot smoother.
(I didn't have to carry out the last request as the person winded up being fired anyways)
evilVNC and other similar remote desktop session monitoring tools are great ways of watching employees , and there are many other ways to retrieve employee emails without risking authenticity . Plain and simple , IT is sometimes henchman work and if you refuse an order , you can easily be the next on the hitlist.
Just remember, when a manager or superior asks you to carry out such tasks that you are considered trusted, and remember what can be done to one person can also be done to the person requesting it . Once they trust you to do their bidding , its not too far off to think at some point later in time they can do your bidding as well willingly or unwillingly , knowingly or unknowingly. Remember, you can always play as a double agent or go rogue .
As for the poor guy being watched, I always recommend trucrypt, multiple layers of encryption + steganography and "accidently" dropping/swapping pc/laptop hard drives
if for any reason you feel you will be terminated or resigning due to hostile work environment in which any accusations true or false can condemn you . Not the college text book recommendation , but the burden of proof is always on the plaintiff and coming from experience and what I've seen, doing so on the contrary to popular belief has saved a few people's @$$'s from losing their jobs
or being held liable for circumstances out of their control.
(Can't say someone did X Y or Z if there are no network logs and a working hard drive with usable forensic data to pull off can you?)