Fatal error: Uncaught Error: Interface "ILIAS\Mail\Signature\Signature" not found in /var/www/html/ilias/components/ILIAS/Mail/classes/Signature/MailInstallationSignature.php:29 Stack trace: #0 {main} thrown in /var/www/html/ilias/components/ILIAS/Mail/classes/Signature/MailInstallationSignature.php on line 29