All emails are bounced back and not sent with Plesk Email Security enabled

Symptoms

• If Plesk Email Security is enabled on the server, all incoming emails are bounced back and all outgoing emails are not sent with the following error:

  Reporting-MTA: dns; host.example.com
  X-Postfix-Queue-ID: 0C3B9189ADCB
  X-Postfix-Sender: rfc822; [email protected]
  Arrival-Date: Mon, 8 Nov 2021 05:46:15

  Final-Recipient: rfc822; [email protected]
  Original-Recipient: rfc822;[email protected]
  Action: failed
  Status: 4.3.2
  Remote-MTA: dns; 127.0.0.1
  Diagnostic-Code: smtp; 421 4.3.2 Service shutting down, closing channel

• /var/log/maillog file contains the following errors:

  amavis[27832]: (27832-01) (!)lookup_sql: sql exec: err=1146, 42S02, DBD::mysql::st execute failed: Table 'emailsecurity.users' doesn't exist
  at (eval 132) line 173., ,

  amavis[27832] (27832-01) (!!)TROUBLE in process_request: sql exec: err=1146, 42S02, DBD::mysql::st execute failed: Table 'emailsecurity.users' doesn't exist at (eval 132) line 173. at (eval 134) line 333.

  amavis[27832]: (27832-01) (!)Requesting process rundown after fatal error

  postfix/smtp[27793]: 52B14194BE9D: to=[email protected], relay=127.0.0.1[127.0.0.1]:10024, delay=139040, delays=139040/0.31/0.09/0.01, dsn=4.3.2, status=deferred (host 127.0.0.1[127.0.0.1] said: 421 4.3.2 Service shutting down, closing channel (in reply to RCPT TO command))

Cause

Corrupted Email Security database

Resolution

1. Log in to Plesk

2. Remove and reinstall the Plesk Email Security extension: How to manage Plesk extensions (install, disable, remove, update)