diff --git a/api/src/Storage/Tracking.php b/api/src/Storage/Tracking.php
index 967494f1ea..17998bcbcb 100644
--- a/api/src/Storage/Tracking.php
+++ b/api/src/Storage/Tracking.php
@@ -799,6 +799,9 @@ abstract class Tracking
 				$notification = new $class();
 				$notification->set_receivers(array($receiver));
 				$notification->set_message($body_cache['text'], 'plain');
+				// add our own signature to distinguish between original message and reply
+				// part. (e.g.: in OL there's no reply quote)
+				$body_cache['html'] = "<span style='display:none;'>----- origianl message -----</span>"."\r\n".$body_cache['html'];
 				$notification->set_message($body_cache['html'], 'html');
 				$notification->set_sender($sender);
 				$notification->set_subject($subject);