When I put in my 2 weeks notice at my last job, I was sent home on the spot. They deactivated my email login before I even got back to my desk. I couldn't even tell my group members that I was leaving...they probably thought I was fired. -_-
At my current job, they seem to do the same thing for the layoffs. When people get laid off, a manager announces it to the team - the former employees immediately lose all access to the email lists and their account...probably to safeguard against nasty emails.