[BUGFIX] Fix mail content fallback

Classes/Service/MailTemplateService.php

@@ -360,7 +360,7 @@ class MailTemplateService {
 		$emailView->assignMultiple($this->markers);
 		$emailView->assign('all_fields', $this->getAllMarker($this->markers));
 
-		if (NULL === $defaultTemplateContent) {
+		if ($template !== NULL) {
 			$emailView->setTemplateSource(\trim($template->getSubject()));
 			$subject = $emailView->render();