[Dovecot] auth: pam_setcred() failed: Error in service module

Hi,

I have a strange problem with authentication. Some users can successfully authenticate and some users can not authenticate. All users use the same client (thunderbird-1.5.0.2-win32-de). At the problematic users i get the following error message:

============ snip =================== auth(default): client in: AUTH 8 PLAIN service=IMAP secured lip=10.24.1.6 rip=10.211.11.1 auth(default): client out: CONT 8 auth(default): client in: CONT<hidden> auth(default): pam(pgerlesb,10.211.11.1): pam_setcred() failed: Error in service module auth(default): client out: FAIL 8 user=pgerlesb auth(default): client in: AUTH 9 PLAIN service=IMAP secured lip=10.24.1.6 rip=10.211.11.1 resp=<hidden> auth(default): pam(pgerlesb,10.211.11.1): pam_setcred() failed: Error in service module auth(default): client out: FAIL 9 user=pgerlesb imap-login: Aborted login: user=<pgerlesb>, method=PLAIN, rip=10.211.11.1, lip=10.24.1.6, TLS ============ snap ===================

The username and password is right. I can "su - <username>" at the dovecot host with the same password. Some other users can authenticate without any problems.

I have set in dovecot.conf:

auth default {
  mechanisms = plain
  passdb pam {
    args = "*"
  }
  userdb passwd {
  }
}

I have configured PAM to do the authentication against Kerberos5. The user data come from an LDAP directory.

What could be the problem?

Thanks Martin Stockinger