diff --git a/UI/WebServerResources/UIxPreferences.js b/UI/WebServerResources/UIxPreferences.js
index 8b1f59f9d..bf6a503f5 100644
--- a/UI/WebServerResources/UIxPreferences.js
+++ b/UI/WebServerResources/UIxPreferences.js
@@ -77,9 +77,9 @@ function savePreferences(sender) {
                 showAlertDialog(_("Please specify an address to which you want to forward your messages."));
                 sendForm = false;
             }
-       
+
         // We check if we can only to internal/external addresses.
-        var constraints = parseInt(forwardConstraints);
+        var constraints = (typeof forwardConstraints != "undefined") && parseInt(forwardConstraints);
         
         if (constraints > 0) {
             // We first extract the list of 'known domains' to SOGo