ext_tables.php

<?php

if (!defined('TYPO3_MODE')) {
	die('Access denied.');
}

// @todo Muss auch noch in die "if (TYPO3_MODE === 'BE') {", weiß nicht ob es Probleme machen könnte.
\TYPO3\CMS\Extbase\Utility\ExtensionUtility::registerModule(
	'SGalinski.sg_mail',
	'web',
	'Mail',
	'',
	[
		'Mail' => 'index, save, sendTestMail',
	],
	[
		'access' => 'admin,user,group',
		'icon' => 'EXT:sg_mail/Resources/Public/Icons/ModuleIcon.svg',
		'labels' => 'LLL:EXT:sg_mail/Resources/Private/Language/locallang.xlf',
	]
);

if (TYPO3_MODE === 'BE') {
	$tables = [
		'tx_sgmail_domain_model_mail',
	];

	foreach ($tables as $table) {
		\TYPO3\CMS\Core\Utility\ExtensionManagementUtility::allowTableOnStandardPages($table);
	}
}