James -
Thanks for the info.  Do you know if the built in Zimbra chat is XMPP, or
something else?   Our end users are using Pandion as a chat client and I'd
like to not change that for them.

Lisa -
We do use Google Apps for our "back-up" mail domain for IT alerting,
actually.  We want to keep more control of our primary corporate email
however.  Plus Zimbra is awesome!