Zimbra mailbox does not support Microsoft Outlook, Office 365, Thunderbird and other email clients environment. Therefore we developed MailsDaddy Zimbra Converter tool to move .tgz file to PST, EML, MBOX, Office 365 and various other platform. It has various advanced features like preview, batch migration etc. The free demo edition of the solution moves up to 20 emails from each folder.
Read more: https://www.mailsdaddy.com/zimbra-converter/