[nbobfin]

OK that's it
Thank you very much

Here is the code to log in zimbra as a user :

SoapProvisioning sp = new SoapProvisioning();
sp.soapSetURI("https://Zimbraserver:7071" + ZimbraServlet.ADMIN_SERVICE_URI);
sp.soapAdminAuthenticate(adminLogin, adminPassword);
ZAuthToken authToken = sp.delegateAuth(AccountBy.name, userLogin, durationInSecond).getAuthToken();
Options options = new Options(authToken.getValue(), "http://Zimbraserver" + ZimbraServlet.USER_SERVICE_URI);
ZMailbox zimbraMailbox = new ZMailbox(options);

And then you have access to all methods described in previous posts.