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)
https://wiki.zimbra.com/wiki/SOAP_API_Reference_Material_Beginning_with_ZCS_8
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-