[Dovecot] dovecot.conf %d problem

[Martins]

Hello,
I have got a problem ir dovecod.conf. I would like to use %d in
default_mail_env = maildir:/var/mail/vhosts/%d/%u/Maildir
but %d seems to be empty. I need it for Postfix virtual domains.
If I use default_mail_env = maildir:/var/mail/vhosts/DOMAIN.ORG/%u/Maildir
mail folders could be accessed.
I wonder, where Postfix virtual domains need to be passed to Dovecot?

more config info:
auth_userdb = static uid=100 gid=100 home=/var/mail/vhosts/%d/%u
auth_passdb = passwd-file /etc/dovecot/pass

Thanks in advance,
M.