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Unable to send email in Plesk: mail transport unavailable

Plesk for Linux kb: technical ABT: Group B

Applicable to:

  • Plesk for Linux

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:

    CONFIG_TEXT: postfix/smtp[715642]: connect to example.com[203.0.113.2]:587: Invalid argument
    postfix/smtp[715642]: 8A0FA1D2090C: to=john.doe@example.com, relay=none, delay=470, delays=470/0.01/0.16/0, dsn=4.4.1, status=deferred (connect to example.com[203.0.113.2]:587:
    Invalid argument)

    CONFIG_TEXT: postfix/qmgr[14111]: warning: connect to transport private/203.0.113.2-: Connection refused
    postfix/error[21724]: 0A1322CF16C: to=john.doe@example.com, relay=none, delay=0.07, delays=0.03/0.01/0/0.02, dsn=4.3.0, status=deferred (mail transport unavailable)

Cause

Postfix is misconfigured.

Resolution

  1. Connect to the server via SSH.
  2. For most cases, manually repairing the mail aspect should be enough, execute plesk repair mail utility:

    # plesk repair mail -y

If the problem is still present:

  • Verify the file /etc/postfix.master.cf. If any values differ from below, edit the file using your preferred editor (such as vi or nano) so they match the values listed below:

# postconf -n | grep -i transport
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

  • Restart the service:

# systemctl restart postfix

If the issue still persists, perform the following action:

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Comments

1 comment
Date Votes
  • I had traffic to port 25 blocked by INOS - probably "inherited" network settings from a previous user of my current IP address.
    Don't waste your time (I did! No thanks IONOS!) and first check if you can connect to any known external mail server using telnet from the command line.
    I.e. $ telnet aspmx2.googlemail.com 25

    If you can't connect - call Customer Service

    0

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