Thanks to the folks at my IT helpdesk for this tip on how to enable your BB to get mail from within Zimbra folders:
- Go to your Messages folder, hit menu key and select Options.
- Go to Email Settings. Hit menu button, select Folder Redirection.
- You will see your mailbox which can be expanded. Expand your inbox and select the folders you want to be sync'd (on my device they're blue instead of grey). Hit menu button, select Save.
Any NEW messages routed to those folders will now be located in the folders on the device as well. As new messages, they'll appear in your Messages folder along with SMSs, MMSs, BBIMs, and other email. Once read, they'll disappear into the appropriate folder(s).