[Dovecot] Understanding dovecot ACLs

[Achim Hut]

Hello List

I am running a Cyrus IMAP that needs to be replaced.

Geting a Dovecot IMAP up and running was surprisingly simple.
My configuration is close to Johnny Chaddas Howto at
http://johnny.chadda.se/2007/04/15/mail-server-howto-postfix-and-dovecot-with-mysql-and-tlsssl-postgrey-and-dspam/

Its a Dovecot 1.1.10 on FreeBSD 6.4

Anyway, while basic setup was easy, i stuck in a couple of details like 
quota, managesieve, etc.
Actual major problem and showstoper is understanding the ACLs the 
confuses me.
So i need a hint to be guided in the right direction.

What i need is a scenario, where user1 can get (for example) full access 
to the folders of user2, read-only access to user3 etc.
A real world example:
Secretary has full access to the mailfolders of her boss, boss has 
read-only acces to the sales-department folder.


My questions:
1) is the possible?
2) can it be done with dovecot-acl files?
3) Namespaces: is it enough to have the private namespace for the job or 
do i need another namespace?
4) if yes, how should this namespace look like?



Thanks for the help
Achim