Transfer Zimbra files to Outlook without losing any data is possible with the Zimbra to Outlook Converter tool.

• Zimbra Converter keeps the folder structure intact throughout the conversion process.
• The Zimbra converter supports a wide range of file types, including PST, MBOX, MSG, EML, EMLX, PDF, OLM, and HTML.
• This software is supportive of cluster change.
• It extracts every necessary piece of mail data, including, but not limited to, the To, Bcc, Cc, Sent, From, Received, and Attachments.

More specifics: http://www.zimbra-converter.com/