diff --git a/addons/mail/static/src/js/mail.js b/addons/mail/static/src/js/mail.js
index 27ffdebfc5a..2f38045b419 100644
--- a/addons/mail/static/src/js/mail.js
+++ b/addons/mail/static/src/js/mail.js
@@ -1409,7 +1409,7 @@ openerp.mail = function (session) {
                 'show_record_name' : false,
                 'show_compose_message' : false,
                 'show_compact_message' : false,
-                'message_ids': [],
+                'message_ids': undefined,
                 'no_message': false
             }, options);