Unable to receive/send mail in Plesk: (!)DENIED ACCESS from IP 203.0.113.2, policy bank

Symptoms

• On a Plesk for Linux server, both sending and receiving emails fails with the following error found in the log file /var/log/maillog:

  plesk amavis[30059]: (!)DENIED ACCESS from IP 203.0.113.2, policy bank ''
  plesk postfix/smtp[12203]: 883A08902100: to=<[email protected]>, relay=127.0.0.1[127.0.0.1]:10024, delay=1004, delays=1004/0.11/0/0, dsn=4.4.2, status=deferred (lost connection with 127.0.0.1[127.0.0.1] while receiving the initial server greeting)

  or

  Nov 12 07:22:53 panel postfix/error[30441]: D450A262495B3: to=<[email protected]>, relay=none, delay=0.72, delays=0.72/0/0/0, dsn=4.4.2, status=deferred (delivery temporarily suspended: lost connection with 127.0.0.1[127.0.0.1] while receiving the initial server greeting)

• The extension Plesk Email Security is installed on the server.

• The option Tools & Settings > Spam Filter > Switch on server-wide greylisting spam protection is disabled.

• The issue is also might be observed after changing outgoing mail IP.

Cause

Bugs in the extension Plesk Email Security:

• For new Plesk Email Security installations: EXTCERT-2813 "Added the inet_acl option to the Amavis configuration file"
  Fixed in:

  • Plesk Email Security 1.0.4 06 April 2020

• For existing Plesk Email Security installations: EXTCERT-2931.
  Fixed in:

  • Plesk Email Security 1.1.0 09 June 2020

Resolution

1. Log in to Plesk.

2. Go to Extensions > Plesk Email Security > Server Settings > Advanced > Debugging

3. Change the value of the option Amavis log level to 1: args passed from client, some more interesting messages and click Save.
   

4. Change the value of the option Amavis log level back to default 0: startup/exit/failure messages, viruses detected and click Save.