Groups in Kolab and Horde

[Timotheus Pokorra]

Hello,

we are investigating the functionality of Kolab and Horde.

One issue is the idea of the groups.
Perhaps people can shed light on our questions.

If you setup an account on Kolab with account type "Group Account",
who is supposed to use the calendar of the group. Does Kolab know,
which users are members of that group?
Or is the idea of a group calendar, that it just holds group events,
and people are added manually to be allowed see the calendar.

Horde does not allow the creation of users, that is fair enough,
because it is all managed through Kolab. But why does it then allow
creation of groups. Members can be added by their email address.
What effect does that have?
Or is it missing functionality? 
Or should I ask this question on the Kronolith list?

Thanks in advance for any hints,

Timo