[TASK] Reading pid from tsfe

Classes/Service/MailTemplateService.php

@@ -39,6 +39,7 @@ use TYPO3\CMS\Extbase\Object\ObjectManager;
 use TYPO3\CMS\Extbase\Persistence\Generic\PersistenceManager;
 use TYPO3\CMS\Extbase\Utility\LocalizationUtility;
 use TYPO3\CMS\Fluid\View\StandaloneView;
+use TYPO3\CMS\Frontend\Controller\TypoScriptFrontendController;
 
 /**
  * MailTemplateService
@@ -290,7 +291,14 @@ class MailTemplateService {
 	 * @throws \TYPO3\CMS\Extbase\Persistence\Exception\IllegalObjectTypeException
 	 */
 	public function sendEmail($isPreview = FALSE) {
-		$pageUid = (int) GeneralUtility::_GP('id');
+		if (TYPO3_MODE === 'FE') {
+			/** @var TypoScriptFrontendController $tsfe */
+			$tsfe = $GLOBALS['TSFE'];
+			$pageUid = $tsfe->id;
+		} else {
+			$pageUid = (int) GeneralUtility::_GP('id');
+		}
+
 		$siteRootId = BackendService::getSiteRoot($pageUid);
 
 		/** @var Template $template */