We currently have a BES server (don't know the specifics) interacting with our Exchange environment. We're also gradually migrating our Cyrus IMAP users over to Zimbra, a few of which use Blackberries. Is it possible to have BES talk to more than one backend server, in this case an Exchange environment as well as Zimbra, or would we need to run a separate BES server for Zimbra? (As you can tell, I'm not very familiar with BES.)