[BUGFIX] Set the sending time via the MailQueue

If a mail is sent via the mail queue, we must also set the sending_time
to prevent the scheduler command controller from sending the same mail
that has been send via the mail queue again.

Classes/Service/MailTemplateService.php

@@ -461,6 +461,9 @@ class MailTemplateService {
 			}
 
 			$dateTime = new DateTime();
+			if ((int)$mailToSend->getSendingTime() === 0) {
+			    $mailToSend->setSendingTime($dateTime->getTimestamp());
+            }
 			$mailToSend->setLastSendingTime($dateTime->getTimestamp());
 			$this->mailMessage->send();
 			$mailRepository->update($mailToSend);