dovecot dies with "Fatal: Socket already exists: /var/spool/postfix/private/dovecot-auth"

Hello,

I currently try to setup a local mail infrastructure: Retrieving them via fetchmail, provide them locally by postfix and use dovecot for IMAP access.

I also want to use SMTP AUTH with SASL via dovecot.

In order to do so I added the following configuration to /etc/postfix/main.cf:

...
smtpd_sasl_auth_enable = yes
smtpd_sasl_authenticated_header = yes
smtpd_sasl_exceptions_networks =
smtpd_sasl_local_domain = $myhostname
smtpd_sasl_path = private/dovecot-auth
smtpd_sasl_security_options = noanonymous
smtpd_sasl_tls_security_options = $smtpd_sasl_security_options
smtpd_sasl_type = dovecot
...

and a corresponding line in /etc/dovecot/dovecot.conf:

...
auth default {
  mechanisms = plain login
  socket listen {
    client {
      path = /var/spool/postfix/private/dovecot-auth
      mode = 0660
      user = postfix
      group = postfix
    }

  }
...

(full dovecot.conf is added to this report).

Now I try to start dovecot by "sudo service dovecot start" and get the message

* Restarting IMAP/POP3 mail server dovecot Last died with error (see error log for more information): Auth process died too early - shutting down
                                                                                                                 [ OK ]

on command line and

2010-06-06 16:07:52 auth(default): Fatal: Socket already exists: /var/spool/postfix/private/dovecot-auth
2010-06-06 16:07:52 dovecot: Fatal: Auth process died too early - shutting down

in the log.

I shut down postfix and deleted the socket manually, but this does not help. Also I set the "count = 1" in the "auth default" section (I found some report that more that one auth process is a problem back in 2006?). The problem prevails.

So I regard this as an error.

Best regards!