[infosyst]

You would want to open a terminal session as the zimbra user and run this command to see what your COS settings are:

zmprov gac -v

It will list each COS and the parameters for that COS. If zimbraCalendarResourceDoubleBookingAllowed is set to TRUE, you would want to run the following command:

zmprov mc {cosname} zimbraCalendarResourceDoubleBookingAllowed FALSE

Where {cosname} is the name of the Class Of Service that you want to change the setting for. If you have mulltiple COS's you will need to run it for each one.

This should effectively gray out the save button and prevent users from double booking.