I don't know how you can say Zimbra is not "enterprise ready"? Zimbra is first and foremost a mail server that competes directly with Exchange. You are not even using the core product, and are using their client which I'm sure was designed to be a client for Zimbra server and not necessarily a client for an Exchange server. So you're taking their free client offering that works just fine with a Zimbra backend, and pointing it to an Exchange server and then saying that Zimbra is not enterprise ready?
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