diff --git a/source/part6.html.erb b/source/part6.html.erb
index d4b806c..85aa5ed 100644
--- a/source/part6.html.erb
+++ b/source/part6.html.erb
@@ -165,7 +165,9 @@ public class HelloWorld {
       <b>After you have submitted the anonymous feedback</b>, send
 	email to the
 	lecturer: <a href="mailto:teemu.roos@cs.helsinki.fi">
-	teemu.roos@cs.helsinki.fi</a>.
+	teemu.roos@cs.helsinki.fi</a>. <b>Important:</b> Include 
+        the magic word IntroAI2020 on the subject line so that Teemu
+        will find your message in his inbox among 5615 unread messages.
   </ol>
 </p>