The option for the user to tick the box that says "Remember me on this computer" when logging in should be removable according to system administrators preference.
There are a number of users who have ticked this option in our testing setup to save logging in and out every day. Unfortunately these users tend to move around so when someone else comes and sits at the desk they have been using the past three days, loads up email, there is the previous users email for them to read, presenting a confidentiality issue.
Obviously I realize this is a education issue on the dangers of ticking this box on a shared system and not logging out properly, but unfortunately this is a fact of life I think as I have some not too bright users who will do it anyway...
It would just be good for administrators intending on using Zimbra in a corporate environment to remove a headache from a feature they won't need. IE's and FF's username/password storing capabilities can be turned off with policies but rejecting cookies is messy and potentially isn't viable.
Worth a feature suggestion?