Postfix Mail server error: can't read SMFIC_OPTNEG reply packet header


2016-11-16 13:23:39 UTC


2017-08-16 17:32:26 UTC


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Postfix Mail server error: can't read SMFIC_OPTNEG reply packet header

Applicable to:

  • Plesk 12.5 for Linux
  • Plesk 11.x for Linux
  • Plesk 12.0 for Linux


An attempt to send email fails with the following error:

Could not send message to SMTP server. Check you have access to send messages via the server and that all To/CC/BCC addresses are valid\

Error: SMTP Server rejected email. Returned:503 5.5.1 Error: need MAIL command

The following error can be found in /usr/local/psa/var/log/maillog :

Aug 21 17:35:46 test postfix/smtpd[18052]: warning: milter unix:/var/spool/postfix/ctmilter/ctmilter.sock: can't read SMFIC_OPTNEG reply packet header: Connection reset by peer


Postfix misconfiguration: Plesk Premium Outbound Antivirus (PPOA) is not installed on server, but the Postfix configuration file includes settings related to PPOA.


  1. Check that Premium Outbound Antivirus is installed (for Plesk versions older, than 12 only).

    /usr/local/psa/admin/sbin/autoinstaller can be used to check it under the 'Mail hosting features'. Alternatively, use rpm :

    # rpm -qa | grep commtouch
  2. Check the Postfix configuration file /etc/postfix/

    # grep smtpd_milter /etc/postfix/

    Make sure that it does not include ctmilter configuration like:

    smtpd_milters = inet:localhost:12768, unix:/var/spool/postfix/ctmilter/ctmilter.sock 
    non_smtpd_milters = inet:localhost:12768, unix:/var/spool/postfix/ctmilter/ctmilter.sock

    Remove unnessesary entries if they are found. The default configuration looks like:

    # grep smtpd_milter /etc/postfix/
    smtpd_milters = , inet:
    non_smtpd_milters = , inet:
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