Mail is not delivered: mail transport unavailable

Created:

2016-11-16 12:44:18 UTC

Modified:

2017-08-16 16:15:57 UTC

1

Was this article helpful?


Have more questions?

Submit a request

Mail is not delivered: mail transport unavailable

Applicable to:

  • Plesk for Linux
  • Plesk 12.0 for Windows
  • Plesk 12.5 for Windows

Symptoms

There are lots of undelivered outgoing emails on the Plesk server. It is not possible to send mail and messages get stuck in the mail queue. The following errors are logged in /var/log/maillog :

postfix/qmgr[14111]: warning: connect to transport private/1.2.3.4-: Connection refused
postfix/error[21724]: 0A1322CF16C: to=<testing@example.com>, relay=none, delay=0.07, delays=0.03/0.01/0/0.02, dsn=4.3.0, status=deferred (mail transport unavailable)

Also the following error may appear in logs in case Amavis content filter is installed on a server:

warning: connect to transport private/amavis: No such file or directory

Cause

  • connection gets refused according to the Postfix configuration in /etc/postfix/master.cf .

  • amavisd software that is not supported in Plesk does not allow sending messages

Resolution

  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
    @example.com plesk-1.2.3.4-:
    @example2.com plesk-2.3.4.5-:
  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/master.cf
    plesk-1.2.3.4- unix - n n - - smtp -o smtp_bind_address=2.3.4.5 -o smtp_bind_address6= -o smtp_address_preference=ipv4
    plesk-2.3.4.5- unix - n n - - smtp -o smtp_bind_address=2.3.4.5 -o smtp_bind_address6= -o smtp_address_preference=ipv4

    # postconf mynetworks
    mynetworks = 127.0.0.0/8 [::1]/128 1.2.3.4/32, 2.3.4.5/32

    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

If Amavis is installed on a server, disable it by commenting the following line in /etc/postfix/main.cf so that it looks like:

#content_filter = amavis:[127.0.0.1]:10024
Have more questions? Submit a request
Please sign in to leave a comment.