Configuration/TCA/Overrides/sys_template.php
<?php
use TYPO3\CMS\Core\Utility\ExtensionManagementUtility;
defined('TYPO3') || die();
(static function (): void {
// Add TypoScript
ExtensionManagementUtility::addStaticFile(
'mail_logger',
'Configuration/TypoScript',
'+Pluswerk AG: Mail Log'
);
})();