Article ID: 123132, created on Oct 11, 2014, last review on Jun 17, 2016

  • Applies to:
  • Plesk for Linux/Unix
  • Plesk 12.0 for Windows
  • Virtuozzo containers for Linux


There are lots of undelivered emails on the Plesk server. It is not possible to send mail and messages get stuck in the mail queue. The connection to the IP is refused :

Mar  6 13:19:33 vps415 postfix/qmgr[14111]: warning: connect to transport private/ Connection refused
Mar  6 13:19:33 vps415 courier-imapd: Connection, ip=[::1]
Mar  6 13:19:33 vps415 postfix/error[21724]: 0A1322CF16C: to=<>, relay=none, delay=0.07, delays=0.03/0.01/0/0.02, dsn=4.3.0, status=deferred (mail transport unavailable)


There can be several causes of this issue. Usually, the connection gets refused according to the Postfix configuration in /etc/postfix/


  1. Review /usr/local/psa/var/log/maillog and find the line with a warning message preceding 'deferred (mail transport unavailable)'. This should help to localize the problem.

  2. Check the transport settings. Compare them with the output below:

        # postconf -n | grep -i trans
        sender_dependent_default_transport_maps = hash:/var/spool/postfix/plesk/sdd_transport_maps
        transport_maps = , hash:/var/spool/postfix/plesk/transport
        virtual_transport = plesk_virtual
  3. Check for transport defined in sender_dependent_default_transport_map:

    # postmap -s /var/spool/postfix/plesk/sdd_transport_maps      plesk-     plesk-
  4. Ensure that the entry from sdd_transport_maps is defined in the first column of "smtp_bind_address". "smtp_bind_address" is an optional numerical network address that the Postfix SMTP client should bind to when making an IPv4 connection.

  5. To be able to connect, smtp_bind_address needs to be defined as mentioned in the mynetworks section and the binding name should be the same as defined in sdd_transport_maps:

    # grep "smtp_bind_address" /etc/postfix/
    plesk- unix - n n - - smtp -o smtp_bind_address= -o smtp_bind_address6= -o smtp_address_preference=ipv4
    plesk- unix - n n - - smtp -o smtp_bind_address= -o smtp_bind_address6= -o smtp_address_preference=ipv4
    # postconf mynetworks
    mynetworks = [::1]/128,

    Note: Starting from Plesk 12, mynetworks should be empty:

    # postconf mynetworks
    mynetworks =
  6. Run the mchk utility to reconfigure postfix:

    # /usr/local/psa/admin/sbin/mchk --without-spam

How to configure the IP address for outgoing mail in Postfix

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