[horde] Share calendars in a multi-tenant environment

["Rubén A. Mansilla"]

Dear Horde List,

we want to use the calendar sharing feature for all the users inside a 
given domain in our current Horde environment. The environment is as 
follows:

- Cloud, multi-tenant, multi-domain
- The current Horde's group-feature is not suitable for our needs, due 
to all the groups are visible for all the platform users, without taking 
into account the domain to which the user belongs
- We think the virtual-host configuration is not an option for us, due 
to we have just one HTTP access point to the Webmail

So, the question is: is there any alternative that restrict the group 
visibility to the users that belongs to a given domain?

Thanks in advance for your reply.

Kind regards,

Rubén Mansilla