Just a note about the logging of said access that a lot of you might be intereseted in:
Originally Posted by uxbod
This file stores a log of all admin actions taken as well as logins to the server.
This will show you all uses of the "View Mail" button.
grep DelegateAuth /opt/zimbra/log/audit.log
This log file keeps track of the IP address, User Agent of the browser, User that the admin is logged in as, and the account that they are viewing.
Hope this helps somebody...