Employees that retire have the option to request their email be changed into a retired account (must be requested by the user):
http://www.oit.uci.edu/policy/facdel.html#retiree
Assume that once you leave, any files that will need to be passed onto the next person will be packaged up and saved on one of the shared drives, or a M: drive of your choice. No files left on the computer of the person retiring will be saved.
Regarding emails - UCI does not grant access to email of the person that's leaving. Any emails that need to be preserved, should be forwarded or saved as a separate attachment.
Please work with your employees to be sure that anything that needs to be preserved for the next person is backed up either by an external drive or stored on a shared drive. Any personal files they want to take with them will need to be copied or removed by the employee's last day.