diff --git a/reference/filter/filters.xml b/reference/filter/filters.xml
index f2fb7d27b5..41afe00bdb 100644
--- a/reference/filter/filters.xml
+++ b/reference/filter/filters.xml
@@ -57,6 +57,7 @@
          <para>
           In general, this validates e-mail addresses against the syntax in
           RFC 822, with the exceptions that comments and whitespace folding
+          and dotless domain names
           are not supported.
          </para>
         </entry>