--- a/plugins/muc/history.lib.lua	Sun Apr 26 14:31:43 2020 +0200
+++ b/plugins/muc/history.lib.lua	Sun Apr 26 19:38:38 2020 +0200
@@ -200,7 +200,27 @@
 end);
 
 module:hook("muc-message-is-historic", function (event)
-	return event.stanza:get_child("body");
+	local stanza = event.stanza;
+	if stanza:get_child("no-store", "urn:xmpp:hints")
+	or stanza:get_child("no-permanent-store", "urn:xmpp:hints") then
+		-- XXX Experimental XEP
+		return false, "hint";
+	end
+	if stanza:get_child("store", "urn:xmpp:hints") then
+		return true, "hint";
+	end
+	if stanza:get_child("body") then
+		return true;
+	end
+	if stanza:get_child("encryption", "urn:xmpp:eme:0") then
+		-- Since we can't know what an encrypted message contains, we assume it's important
+		-- XXX Experimental XEP
+		return true, "encrypted";
+	end
+	if stanza:get_child(nil, "urn:xmpp:chat-markers:0") then
+		-- XXX Experimental XEP
+		return true, "marker";
+	end
 end, -1);
 
 return {