Detailed instructions for setting up the Zimbra mobile service can be found here:
http://www.zimbra.com/pdf/Zimbra%20Collaboration%20Suite%20Mobile%20Beta.pdf

Text of this file is below:

April 2006 Introducing Zimbra Mobile Beta

Zimbra Mobile is the Zimbra synchronization program to provide mobile data access for users of the Treo™ 650 smartphone and devices with Windows® Mobile 5 (WM5) software, including smartphones and PocketPCs. This release supports synchronization of calendar and contacts on WM5 devices via Mobile Outlook®, and calendar on the Treo 650 smartphone via Palm™ VersaMail.

Email synchronization is not supported with this release, but IMAP could be used for mail access, as a workaround.

This is a beta release of Zimbra Mobile and you may experience product quality issues when using it to synchronize. The majority of WM5 testing has been with the Treo 700w, but our experience suggests that other WM5 devices are similar. Limited testing has been performed with devices using Windows Mobile 2002 or 2003.

Zimbra Mobile uses the native software installed on the devices. No additional client software is required on the device. You configure the device software for Zimbra Mobile similarly to how you configure the device to sync against Microsoft® Exchange. The following fields may need to be configured:

Server address. Type: https://a.mail.sonomait.com

If the above is returning slow responses, use http://a.mail.sonomait.com.

User name. Type the user's primary Zimbra account name. The domain is configured separately.

Domain. Type the user's Zimbra mail domain name.

Zimbra Mobile will be priced separately from the Zimbra Collaboration Suite Network Edition and Small Business Edition. During the beta period, the Zimbra Mobile will be included for free with the ZCS Network Edition and Small Business Edition. Zimbra Mobile pricing will be announced when Zimbra Mobile is GA released.

Known issues in this beta release If you create a meeting using the device, the attendees will not be notified via email of the meeting. Push notification of changes is not supported.

Note: Some users may experience configuration difficulty if using SSL. WM5 includes a limited number of root certificates and it may be necessary to install your server's signing CA's certificate on the device in order to use SSL.