[Dovecot] Public Namespace & ACL & Virtual Users

[Fintec]

Background:

I am wanting to create shared folders (public namespace) with access
control lists on the sub directories.

Our implementation of dovecot (v1.0b7) uses many virtual users and
domains and 1 actual user (vmail), all using maildir. So far I have
successfully created the public namespace (Public_Folders) which every
user can access but I'm having difficulty restricting access using ACls.

When trying to implement the dovecot ACL plug-in I followed the wiki
instructions and created a "dovecot-acl" file within Public_Folders
containing:
owner lrwstiekxa
user=user1 at domain.com lrwstiek

However this doesn't appear to do anything. All users can still access
Public_Folders so I have a couple of questions that hopefully someone
can help me with...

1) Is it possible to use the dovecot's ACL plug-in on a Public name
space?

2) Is it possible to create dovecot-acl files with virtual usernames,
i.e. user1 at domain.com or does it have to be actual users, i.e. vmail?

3) Is it possible to restrict access within the namespace definition,
i.e. set up another public namespace restricted to manager at domain.com?

4) Is ACL accepts & denies logged somewhere other than /var/log/maillog
(my default)?

4) Is anyone successfully set-up an environment with a public namespace
and ACLs?

Any help would be greatly appreciated.

Gavin