--- a/mod_smacks/mod_smacks.lua	Mon Sep 10 21:02:26 2012 +0200
+++ b/mod_smacks/mod_smacks.lua	Mon Sep 10 21:11:04 2012 +0200
@@ -84,7 +84,7 @@
 			queue[#queue+1] = cached_stanza;
 		end
 		local ok, err = _send(stanza);
-		if ok and #queue > max_unacked_stanzas and not session.awaiting_ack then
+		if ok and #queue > max_unacked_stanzas and not session.awaiting_ack and attr and not attr.xmlns then
 			session.awaiting_ack = true;
 			return _send(st.stanza("r", sm_attr));
 		end