[Dovecot] Virtual domain support using more than one MySQL database

[Dragiša Durić]

For historical reasons I am stuck with situation where hosted domain
users have their Mailbox info in mysql enabled vpopmail and our ISP's
users have their info in nss_mysql.

While I can easily move my users from vpopmail's mysql database to
something more "native" to Dovecot, I see no problem to configure
Dovecot, as I've already configured Postfix, to use this database
directly and access mailboxes without problem. And I would not like to
make separate auth database for ISP's users, as I don't like to have two
watches when one suffice.

Under courier-imap, I've configured my vpopmail domains to authenticate
using it's vchkpw module, and mysql was left to me to be configured to
use nss_mysql. It works well. Is it possible under Dovecot, and how? 

Is it possible to to MySQL auth using two different databases? It would
be the best.

TIA,
dd