Mail does not work after restoring Plesk after disaster: No such user in mail authorization database

Symptoms

• After restoring Plesk due to disaster. Mail stopped working;

• The following error can be found in /var/log/maillog:

  CONFIG_TEXT: dovecot_authdb_plesk[5239]: No such user 'john.doe@example.com' in mail authorization database

• mchk ( /usr/local/psa/admin/sbin/mchk ) utility does not restore authentication database. The below errors can be found in Plesk logs /var/log/plesk/panel.log:
  

  CONFIG_TEXT: ERR [panel] Non-UTF data for mail account: john.doe@example.com

Cause

Mailbox passwords can not be decrypted with the /etc/psa/private/secret_key

Resolution

1. Log in to Plesk server using SSH

2. Backup the original key:

   # cp /etc/psa/private/secret_key /etc/psa/private/secret_key.orig

3. Restore the secret key from the old server, put it in the correct directory /etc/psa/private/secret_key and rerun mchk utility:

   # cp /etc/psa/private/secret_key /etc/psa/private/secret_key.orig
   # cp /old/etc/psa/private/secret_key /etc/psa/private/secret_key

   Otherwise, reset all mail passwords with the Plesk mass password reset script using --mailaccounts option.

Additional information

Plesk Mass Password Reset Script