- Check if hook is enabled before constructing hook notification items

- Skip/early exit email hook if notification item is not a VCALENDAR

radicale/hook/none.py

@@ -2,5 +2,10 @@ from radicale import hook
 
 
 class Hook(hook.BaseHook):
+    @property
+    def enabled(self) -> bool:
+        """Check if this hook is enabled."""
+        return False
+
     def notify(self, notification_item):
         """Notify nothing. Empty hook."""