diff --git a/resources/prosody-plugins/mod_muc_domain_mapper.lua b/resources/prosody-plugins/mod_muc_domain_mapper.lua
index ea744f440f..c9c7a53712 100644
--- a/resources/prosody-plugins/mod_muc_domain_mapper.lua
+++ b/resources/prosody-plugins/mod_muc_domain_mapper.lua
@@ -11,12 +11,14 @@ if not muc_domain_base then
     return
 end
 
+local log_not_allowed_errors = module:get_option_boolean('muc_mapper_log_not_allowed_errors', false);
+
 local util = module:require "util";
 local room_jid_match_rewrite = util.room_jid_match_rewrite;
 local internal_room_jid_match_rewrite = util.internal_room_jid_match_rewrite;
 
 -- We must filter stanzas in order to hook in to all incoming and outgoing messaging which skips the stanza routers
-function filter_stanza(stanza)
+function filter_stanza(stanza, session)
     if stanza.skipMapping then
         return stanza;
     end
@@ -36,6 +38,16 @@ function filter_stanza(stanza)
         if stanza.attr.from then
             stanza.attr.from = internal_room_jid_match_rewrite(stanza.attr.from, stanza)
         end
+
+        if log_not_allowed_errors and stanza.name == 'presence' and stanza.attr.type == 'error' then
+            local error = stanza:get_child('error');
+            if error and error.attr.type == 'cancel'
+                    and error:get_child('not-allowed', 'urn:ietf:params:xml:ns:xmpp-stanzas')
+                    and not session.jitsi_not_allowed_logged then
+                session.jitsi_not_allowed_logged = true;
+                session.log('error', 'Not allowed presence %s', stanza);
+            end
+        end
     end
     return stanza;
 end