Better error messages if the "Send Test Email" button fails.

app/assets/javascripts/admin/controllers/admin_email_index_controller.js

@@ -31,14 +31,21 @@ Discourse.AdminEmailIndexController = Discourse.Controller.extend({
       @method sendTestEmail
     **/
     sendTestEmail: function() {
-      this.set('sentTestEmail', false);
+      this.setProperties({
+        sendingEmail: true,
+        sentTestEmail: false
+      });
 
-      var adminEmailLogsController = this;
+      var self = this;
       Discourse.ajax("/admin/email/test", {
         type: 'POST',
         data: { email_address: this.get('testEmailAddress') }
       }).then(function () {
-        adminEmailLogsController.set('sentTestEmail', true);
+        self.set('sentTestEmail', true);
+      }).catch(function () {
+        bootbox.alert(I18n.t('admin.email.test_error'));
+      }).finally(function() {
+        self.set('sendingEmail', false);
       });
 
     }

app/assets/javascripts/admin/templates/email_index.js.handlebars

@@ -13,6 +13,9 @@
 </table>
 
 <div class='admin-controls'>
+  {{#if sendingEmail}}
+  <div class='span15 controls'>{{i18n admin.email.sending_test}}</div>
+  {{else}}
   <div class='span5 controls'>
     {{textField value=testEmailAddress placeholderKey="admin.email.test_email_address"}}
   </div>
@@ -20,4 +23,5 @@
     <button class='btn' {{action sendTestEmail}} {{bind-attr disabled="sendTestEmailDisabled"}}>{{i18n admin.email.send_test}}</button>
     {{#if sentTestEmail}}<span class='result-message'>{{i18n admin.email.sent_test}}</span>{{/if}}
   </div>
+  {{/if}}
 </div>

config/locales/client.en.yml

@@ -1414,6 +1414,8 @@ en:
         title: "Email"
         settings: "Settings"
         all: "All"
+        sending_test: "Sending test Email..."
+        test_error: "There was an issue sending email. Please check your settings and try again."
         sent: "Sent"
         skipped: "Skipped"
         sent_at: "Sent At"