Go to Edit Options in My FlyerTalk and make sure that under the Messaging & Notification heading the Default Thread Subscription Mode is set to have you receive email notifications (instantaneously, daily or weekly). Then, scroll down and click on Save Changes. Your Subscribed Threads list will show which ones are set for email notifications. I have no idea how to edit those preferences, however, you can always unsubscribe and resubscribe to a thread and opt to receive email notifications on the new subscription.