on a Fedora 11 x64 server.
After the last 2 updates to latest version of Zimbra, no user is possible to write into any calendar (even in his own), if the Mail tab is disabled and therfore invisible for this user.
If I check the "Mail" checkbox for the user and re-login the user, the Mail tab is visible and the user is able to make schedules to his own and shared calendars.
As I remember, I hadn't the behavior, at the first version, I installed. It was version: zcs-6.0.5_GA_2213.F11_64.20100203001950
It would be nice, if somebody could give me advices, how to use the calendar without viewing the mail tab. We don't use the mail functionality in Zimbra at all!