Just a quick note:
We rolled out Zimbra back in October to our 2,000+ users with some last minute account insanity. Aside from quickly adding over one hundred last minute accounts, the roll out was a success. We’ve had a few issues since then, but nothing major and all issues were addressed by Zimbra’s support team within a reasonable amount of time.
So far it seems to be a hit with most of our staff and I’m extremely happy with our decision. If you’re looking for an email system, I definitely recommend checking them out.