[Dovecot] Public namespaces with global ACLs 1.2+

Hi,

I'm having trouble to get ACLs working in a more restrictive way with
namespaces. I would like to grant certain users the ability to create
new mailboxes in a public namespace e.g. "Public/Newsletters" etc.

It works when I add the users to a ".DEFAULT" ACL file like this: user=username lrwk

Anyway I'd like to limit their permissions on the Namespace "Public",
or even better - being more restrictive, on "Public/Newsletters".
Neither global ACL files for "Public" nor "Newsletters" nested in the
global path seem to work. For now only the .DEFAULT ACL (/var/vmail/ domain/etc/acls/.DEFAULT) seems to mitigate the problem which is
undesirable.

dovecot -n excerpt:

plugin: acl: vfile:/var/vmail/%d/etc/acls:cache_secs=300

Thanks Thomas