diff --git a/content/u/advent-calendar/06/contents.lr b/content/u/advent-calendar/06/contents.lr
index fe7c70b..a4a9d5e 100644
--- a/content/u/advent-calendar/06/contents.lr
+++ b/content/u/advent-calendar/06/contents.lr
@@ -35,7 +35,7 @@ prefixes from SixXs. The following URLs might be helpful:
 * [The Hack4Glarus development
   ticket](https://redmine.ungleich.ch/issues/8673)
 * [The ipv6ula open source project hompage](/u/projects/ipv6ula/)
-
+* [The announcement on the IETF mailing list](https://mailarchive.ietf.org/arch/msg/ipv6/fFpPHY55pwKlEopyyAZyZI8azg0/)
 
 ## Background