[TASK] fixing missing initilization of site root id

Classes/Controller/MailController.php

@@ -315,6 +315,9 @@ class MailController extends ActionController {
 		$selectedExtension, $selectedTemplate, $selectedLanguage, $selectedContent, $selectedSubject,
 		$selectedFromName, $selectedFromMail, $selectedCc, $selectedBcc, $selectedReplyTo
 	) {
+		$pageUid = (int) GeneralUtility::_GP('id');
+		$siteRootId = BackendService::getSiteRoot($pageUid)['uid'];
+
 		/** @var Template $template */
 		$template = $this->templateRepository->findOneByTemplate(
 			$selectedExtension, $selectedTemplate, $selectedLanguage, $siteRootId

Classes/Service/MailTemplateService.php

@@ -435,6 +435,9 @@ class MailTemplateService {
 		$mail->setSendingTime($sendingTime);
 		$mail->setReplyTo($this->replyToAddress);
 
+
+		$mail->setSiteRootId($this->replyToAddress);
+
 		$mailRepository = $this->objectManager->get(MailRepository::class);
 		$mailRepository->add($mail);
 		$this->persistenceManager->persistAll();