Unable to send or receive email on the Plesk server: Milter service inet:127.0.0.1:12345: Connection refused

Symptoms

• In an attempt to send or receive an email the process fails with the following error message in the  /var/log/maillog file:

  CONFIG_TEXT: postfix/smtpd[1742]: warning: connect to Milter service inet:127.0.0.1:12345: Connection refused

Cause

MagicSpam extension was removed previously, however its leftovers exist in Postfix  /etc/postfix/main.cf configuration file.

Resolution

1. Log into the server via SSH.
2. Create a backup for the /etc/postfix/main.cf file:
   

   # cp -pr /etc/postfix/main.cf /etc/postfix/main.cf.back

3. Using the vi text editor open the /etc/postfix/main.cf file.
4. Find the line below and change it from:
   

   CONFIG_TEXT: smtpd_milters = , inet:127.0.0.1:12768, inet:127.0.0.1:12345

   To

   CONFIG_TEXT: smtpd_milters = , inet:127.0.0.1:12768

5. If non_smtpd_milters directive is present and contains the inet:127.0.0.1:12345 part, modify it the same way.
6. Save changes.
7. Restart Postfix to apply the changes:
   

   # systemctl restart postfix