May you hate Zimbra Desktop and want to use Outlook without paying for outlook connector.
If so you can use Zimbra server as IMAP but the tricky in that is the incoming port.
In the Advanced tab, enter the following settings:
• “993” for the “Incoming server (IMAP)”
• “SSL” for the Incoming server encrypted connection
• "25” for the “Outgoing Server (SMTP)”
• "TLS” for the Outgoing server encrypted connection
If the Outgoing server doesn't work with port 25 the try 587 or 26.