[Dovecot] X.509 certificate based IMAP login

[dovecotlist]

Hello list,

The dovecot version is 1.2.6 running on Solaris x86 11 (nv-b91).
The relevant configuration lines are:

  passdb ldap {  # LDAP database (doc/wiki/AuthDatabase.LDAP.txt.)
    args = /pfx/etc/dovecot/dovecot-ldap.conf
  }

The file dovecot-ldap.conf is correct and LDAP authentication is
working well.

We would like to make it possible for users with a X.509 client
certificate to log in without providing LDAP or any other
credentials. Is there something like:

  passdb x509 {
    args = /pfx/etc/dovecot/dovecot-caroots.pem
    nopwd = yes
  }

...avaibable, or is there another solution?

Thanks,
Brian