From MCS IT Wiki
You can configure a Windows Mobile device for e-mail only syncing via the standard protocols. Since each device can be customized by carrier, you should be able to go with the information provided on the main Mail page.
Once that is set up, Zimbra will pretend to be an Exchange server as far as your phone is concerned.
- Remove any existing ActiveSync pairing. Windows Mobile devices can only sync with a single Exchange Server.
- Open ActiveSync (Start -> Programs -> ActiveSync)
- Select "Menu", then "Configure Server"
- The server configs are as follows:
- Server address: zimbra.anl.gov (Check the box for SSL)
- The next two boxes come from your e-mail address. Specifically:
- Username is your everything to the left of the @ sign in your address, and domain is zimbra.division.anl.gov. (eg. firstname.lastname@example.org becomes Username: stace, Domain: zimbra.mcs.anl.gov)
- Select which modules you wish to sync, choosing the individual settings for each one.