diff --git a/plone/app/discussion/browser/controlpanel.pt b/plone/app/discussion/browser/controlpanel.pt
index 3fb5288..25af7f6 100644
--- a/plone/app/discussion/browser/controlpanel.pt
+++ b/plone/app/discussion/browser/controlpanel.pt
@@ -17,7 +17,9 @@
 
 
 <body>
-<div id="content" metal:fill-slot="prefs_configlet_content">
+<div id="content" 
+     tal:attributes="class python: view.invalid_mail_setup and 'invalid_mail_setup'"
+     metal:fill-slot="prefs_configlet_content">
 
     <script type="text/javascript"
         tal:attributes="src string:${context/portal_url}/++resource++plone.app.discussion.javascripts/controlpanel.js">
diff --git a/plone/app/discussion/browser/controlpanel.py b/plone/app/discussion/browser/controlpanel.py
index a52aeac..d8b89c4 100644
--- a/plone/app/discussion/browser/controlpanel.py
+++ b/plone/app/discussion/browser/controlpanel.py
@@ -8,6 +8,8 @@ from plone.app.registry.browser import controlpanel
 
 from plone.registry.interfaces import IRegistry
 
+from zope.component import getMultiAdapter
+
 from z3c.form import button
 from z3c.form.browser.checkbox import SingleCheckBoxFieldWidget
 
@@ -69,12 +71,23 @@ class DiscussionSettingsEditForm(controlpanel.RegistryEditForm):
                                                       "info")
         self.request.response.redirect("%s/%s" % (self.context.absolute_url(), 
                                                   self.control_panel_view))
+
+        
+class DiscussionSettingsControlPanel(controlpanel.ControlPanelFormWrapper):
+    form = DiscussionSettingsEditForm
+    index = ViewPageTemplateFile('controlpanel.pt')
+
     def anonymous_discussion_allowed(self):
-        # Check if anonymous comments are allowed in the registry
+        """Return true if anonymous comments are allowed in the registry.
+        """
         registry = queryUtility(IRegistry)
         settings = registry.forInterface(IDiscussionSettings, check=False)
         return settings.anonymous_comments
 
-class DiscussionSettingsControlPanel(controlpanel.ControlPanelFormWrapper):
-    form = DiscussionSettingsEditForm
-    index = ViewPageTemplateFile('controlpanel.pt')
+    def invalid_mail_setup(self):
+        """Return true if the Plone site has a valid mail setup.
+        """
+        ctrlOverview = getMultiAdapter((self.context, self.request),
+                                       name='overview-controlpanel')
+        return ctrlOverview.mailhost_warning()
+        
\ No newline at end of file
diff --git a/plone/app/discussion/browser/javascripts/controlpanel.js b/plone/app/discussion/browser/javascripts/controlpanel.js
index 1908782..5cf76da 100644
--- a/plone/app/discussion/browser/javascripts/controlpanel.js
+++ b/plone/app/discussion/browser/javascripts/controlpanel.js
@@ -36,6 +36,21 @@
      **************************************************************************/
     $(window).load(function () {
 
+        /**********************************************************************
+         * Do not allow to change the mail settings if there is no valid mail
+         * setup.
+         **********************************************************************/
+        var invalid_mail_setup = $("#content").hasClass("invalid_mail_setup");
+        if (invalid_mail_setup === true) {
+            $.disableSettings([
+                $('#formfield-form-widgets-moderator_notification_enabled'),
+                $('#formfield-form-widgets-user_notification_enabled')
+            ]);
+        };
+        
+        /**********************************************************************
+         * If commenting is disabled globally, disable all commenting options.
+         **********************************************************************/
         var commenting_enabled_globally = $("#form-widgets-globally_enabled-0").attr("checked");
         if (commenting_enabled_globally === false) {
             $.disableSettings([
@@ -46,11 +61,7 @@
                 $('#formfield-form-widgets-moderator_notification_enabled'),
                 $('#formfield-form-widgets-user_notification_enabled')
             ]);
-        }
-        
-        /**********************************************************************
-         * If commenting is disabled globally, disable all commenting options.
-         **********************************************************************/
+        };
         $("input[name='form.widgets.globally_enabled:list']").live("click", function (e) {
             if ($(this).attr("checked")) {
                 // commenting globally enabled
@@ -75,11 +86,11 @@
             }
         });
 
-        /*
+        /**********************************************************************
          * Remove the disabled attribute from all form elements before 
          * submitting the form. Otherwise the z3c.form will raise errors on
          * the required attributes.
-         */
+         **********************************************************************/
         $("input[name='form.buttons.save']").live("click", function (e) {
             e.preventDefault();
             $('#formfield-form-widgets-anonymous_comments').removeAttr('disabled');
