Does anyone have tried to work with a Zimbra Server and the calendar feature?

I’m trying for my organization the eM Client, but I’fe fount that I can’t connect to my Zimbra Calendar, using even the /dev/ trick. Does anyone have experienced similar trouble?

What protocol are you using against zimbra.
It seems the only way now to have thing working i zimbra is:
 Imap       = email
 Carddav  = galsyn globaladresslist + personal contactlist
 Caldal     = your calander or other calenders

I can’t figure out how one should setup calenderappointments to see if another user in zimbra is free or busy(freebusy-system of the mailserver). and not sure how one could map other users shared calender up. it would be awful lot of caldav-accounts if one have to add one and one user calender to the list.

Currently I have tested activesync against zimra. I get airsync errors. I also read on this forum that activesync does not seem to be suportet in emclient no longer due to a licenseproblem. EWS is supported in zimbra, however that protocol does not work either against zimbra.

It would be great if emclient would support zimbra api accessed by http/https. Currently that means zimbra soap(complete. everything is possible through this api!) or rest api (better supported in the future)
And another thing that would be great if emclient would support zimbra api through http/https, one also could have it work with SSO-authentication.

-Zimbra user and admin-