Mail Stucked in queue in Plesk: SQLSTATE[HY000] [1045] Access denied for user 'user1'@'localhost' (using password: YES)

Symptoms

• Plesk Email Security extension is installed on the server

• In an attempt to access Plesk Email Security the following error is shown:
  

  SQLSTATE[HY000] [1045] Access denied for user 'user1'@'localhost' (using password: YES)

• Mail stuck in the queue with below message in /var/log/maillog:

  Feb 5 12:07:05 admin amavis[211238]: (211238-01) (!)connect_to_sql: unable to connect to DSN 'DBI:mysql:database=emailsecurity;host=localhost;port=3306': Access denied for user 'user1'@'localhost' (using password: YES)
  Feb 5 12:07:05 admin amavis[211238]: (211238-01) (!!)TROUBLE in process_request: connect_to_sql: unable to connect to any dataset at (eval 123) line 253.
  Feb 5 12:07:05 admin amavis[211238]: (211238-01) (!)Requesting process rundown after fatal error

  ---

  (delivery temporarily suspended: connect to 127.0.0.1[127.0.0.1]:10024: Connection refused)

Cause

Plesk Email Security was not correctly installed.

Resolution

1. Login to Plesk

2. Remove Plesk Email Security extension under Home > Extensions

3. Connect to the server via SSH

4. Resubmit message to the queue:

   # postsuper -r ALL

5. Afterward, install Plesk Email Security back if it is required.