Simply put, Try Zimbra. (Score 1)

Being a university, you should setup your own servers and use Zimbra mail on them. In the furture, you could consider having student interns maintain the system. Zimbra for me was a very easy install, it has a great web interface complete with collaboration and built in wiki. It is a very simple interface for administrators. Also a web interface. That means access on campus and off for clients and admins. Great system that works very well.