If you upgraded to version 12.0.0 and your central webmail isn't working, run:
cat /var/local/enhance/orchd.json | jq -r '.email_secret.secret'
Then find your central webmail website, go to the file manager, edit public_html/config/config.inc.php and replace the value of $config['orchd_key'] with the string from the above command.
This is only for the central webmail on the control panel server, it's not required for the mail.customerdomain that runs on every mail server.
