[Dovecot] Help with vpopmail authentication

[Fran Márquez]

Hello,

Currently I have a qmail server with vpopmail+courierImap. I want setup
a new server in DMZ for proxy IMAP connections and I have a doubt with
authentication method.

I've read that dovecot can use a vpopmail driver for authentication. As
my user database/password is stored by vpopmail, I think that this would
be the best method for check the auth logins against dovecot.

But I've read the docs and many examples availables on WWW and I haven't
found any reference to validate against an *external* vpopmail server.

The examples configuration doesn't contain any host/port, so I suppose
that driver try to use a local vopomaild. In my case, I only want
dovecot for proxying IMAP connections to my current mail server, without
store mails or user/password info in dovecot server, because all that
info is already stored in real mailserver.

The ideal scenario would be this:

user ---IMAPs----> dovecot ----- IMAP ---> mailserver

Any advice will be wellcome.

Regards and thank you very much in advance