jgab's picture

This is the answer I received on the Zimbra forum:

"Yes you could either use POP or the more preferable IMAP to serve the Outlook clients. Using fetchmail you could pull down the emails from your ISP and then distribute them via Zimbra; alternatively why not receive emails directly to your Zimbra server and then use one of the myriad of backup MX services on the internet to act as a secondary"

Best regards,