We've been using Zimbra for staff, faculty, and student email for over five years. Although some might differ, it has been a successful deployment overall and our users have come to take rich access to their email from anywhere for granted. We were in the private cloud before cloud was cool.
But today Zimbra has greater competition in the EDU space in the form of "free" hosted email from Microsoft and Google. When we last looked at these options there were enough obvious caveats, gotchas, and not-so-hidden costs that the value proposition was arguable. Today competition between these two giants is driving the market and it's getting tougher for an EDU to justify the cost of hosting their own email.
Unfortunately, Zimbra doesn't seem well positioned to meet this challenge. Zimbra and VMware have preferred to leave public cloud Zimbra offerings to their service providers - a logical choice given their position in the market. Unfortunately that model no longer seems competitive in the EDU space where service providers have little reason to host large volume email domains for free.
If Zimbra wants to be competitive in the EDU market they're going to have to be more aggressive on both pricing and marketing. That probably means free Network Edition licensing for EDU and considerable work on exposing the TCO of these solutions. Certainly some will still see value in hosting their own email, but once management hears the siren call of "free" and "Outlook" there may be no room for argument.