I have a client who resides in and office building with common shared conference room. The client asked if I could create a zimbra calender that is accessable to both them and other tenants of the building so that the conference room could be reserved/scheduled.

I've thought of different options, but wanted to hear your input which is best:

#1 - create a subdomain with it's own website and calendar...this may not be a zimbra calendar but instead a php/mysql based calendar.

#2 - create a new account on the clients zimbra server, with just the calendar available for use, share the calendar, and have tenants of the building log into this user account to make appointments for the conf room.

I think the issue with this is that when the other tenants access the calendar, the attendants in particular, the global address list will now be public to the other tenants, correct? ...or can I turn the GAL off for just this calendar?

#3 - add a new domain name, a sub domain, to the clients zimbra server, and have tenants access the calendar via this domain name.

This will solve the problem with the public GAL, but in this case the calendar can not be shared with the other domain, correct? Or can you share a calendar over multiple domains (2)?

#4 - Create a zimbra calendar that is available to only the client and tenants...but I don't think zimbra calendars can be accessable outside zimbra....?

I'd like to use a zimbra calendar because it's SO awesome at scheduling!

info and any help is appreciated!