diff --git a/docs/releasenotes.rst b/docs/releasenotes.rst
index 5f5a898386a67da178934487b9ff54de5f61026a..d229b0f173732cbf57b83d5751588b49ee7fec6d 100644
--- a/docs/releasenotes.rst
+++ b/docs/releasenotes.rst
@@ -68,6 +68,14 @@ Dropped support for Debian 10 (Buster).
   * Environment indicator can now be collapsed by clicking on the
     arrows on the left side.
 
+* ``mail_server`` role
+
+  * Protection against forging of sender addresses has been
+    implemented, preventing logged-in users from using arbitrary
+    sender mail addresses, even if authenticated. Authenticated users
+    can use either their own login as sender, or one of the aliases
+    that are associated with their mail account.
+
 * ``web_server`` role
 
   * Added parameter ``environment_indicator`` which is used on the