Blacklist the topics-related notification events for mixpanel.

lib/stats.js

@@ -245,7 +245,11 @@ function configureMixpanel(statsHandlers, config) {
     client_error_5xx: true,
     unread_notification_sent: true,
     charge_failed: true,
-    suggest_room: true
+    suggest_room: true,
+    topics_notification_email: true,
+    topic_notification_email: true,
+    reply_notification_email: true,
+    comment_notification_email: true,
   };
   var Mixpanel = require('mixpanel');