I am currently testing Roadsync (Sync With Microsoft Exchange Server & Corporate Outlook Email Via Remote Email Access via ActiveSync on Your Smartphone.) as a means to synchronize my mobile and Zimbra. so far this seems to be working rather nicely,
I have access to my inbox, I can subscribe to subfolders in, and out of the Inbox tree, sending works fine, calendar/gal gets synced too.
However I can't use the "Search server" feature. Is this currently not implemented serverside yet ?