diff --git a/README.adoc b/README.adoc
index b03f421..650a688 100644
--- a/README.adoc
+++ b/README.adoc
@@ -9,3 +9,6 @@
 It's also used to build and publish the website.
 
 Please see https://james.apache.org/james-site/latest/index.html[online documentation website] or the `docs/` folder.
+
+IMPORTANT: The website must not be published as Apache Source files.
+The reason is the antora ui-bundle uses MPL 2.0 license and we can't mix it with ASF 2.0 https://issues.apache.org/jira/browse/LEGAL-530 .