I have been reading a lot of cases where people are having difficulty in
sharing their calendars in Outlook. We are having the exact opposite problem.
It appears that everyone in our organization can open everyone else’s
calendar as a shared calendar, and even make changes! The only way to prevent
changes is to make an event a private item. None of the users checked has
opted to share their calendar to more than one or two people and some do not
share to anyone (the permission is set at default with none as permissions.)
I even created a test user with no rights other than domain user and the test
user could open my calendar, which was set as default with no permissions.
The test user was using Outlook 2000. I have Outlook 2003 SP2.

Our environment is: Exchange 2003 SP2 (clustered), Outlook 2003, SP2 on down
to Outlook 2000, Windows 2003 hybrid domain with about 3500 users. Because of
our hybrid domain, we do not have any group policies in place except for the
default.

I am thinking that this is a permissions issue on Exchange and not Outlook,
but I don’t know where to begin. I don’t want to start tinkering with
permissions without at least knowing the default minimum permissions that
should exist. Thanks for your help and suggestions.