[Dovecot] Deliver virtual user's mail to a specific namespace?

[Brian Schang]

Hello:

I have virtual users set up for the various mailing lists that I 
subscribe to. Everything has been working well in both Postfix and 
Dovecot. Postfix is configured to deliver to a specific mbox file within 
my mbox mail root. I can access retrieve and read email via Dovecot 
without any issues.

Now I want to make my setup more robust and have these messages 
delivered to a maildir namespace.

I have configured the LDA within the Postfix master.cf file:
dovecot   unix  -       n       n       -       -       pipe
  	flags=DRhu user=vmail:vmail argv=/usr/lib/dovecot/deliver -f 
${sender} -d ${recipient}

I have configured the 'dovecot' transport within Postfix in the 
transport file:
t...@lists.schang.net           dovecot:

In dovecot.conf I have set up the namespace as follows:
namespace private {
        separator = /
        prefix = "Lists/"
        location = maildir:~/MailLists
        subscriptions = yes
}

I'm having a hard time specifying the "Lists/" namespace in my userdb 
passwd-file:
test:{PLAIN}linux:2000:200::/home/brian::userdb_mail=maildir:Lists/test

I can't get the userdb_mail portion to work. For this user, 
't...@lists.schang.net', how do I tell Dovecot/deliver to put the 
message in the 'test' mailbox within the 'Lists/' namespace?

I'd appreciate any insight.

Thank you.

--
Brian Schang