[Dovecot] Mixing system and virtual users

I am almost done migrating to a new server using Dovecot + Postfix + Postfixadmin/MySQL. I am a bit confused about how to mix the system (pam) and virtual (SQL) users though.

I see that in dovecot.conf, there is a default_mail_env variable but that seems to apply to both cases. I really need a default for each type of authentication.

My virtual users are in /var/vmail/domain/user and my system users are in /home/user/Maildir

any ideas? I can get one or the other to work but not both at this point.

Thanks,

Tim