Unfortunately, those links are sometimes busted. We don't know why.
But really - the volume of them (cause you get one every time either I, Beate, or Daven approves images) can fill up your mailbox!
To turn them off, go to the gallery, and click on My Profile. YOu'll see your subscriptions listed on the left. Check them all off, and click Delete Subscriptions, and the flood of useless emails will stop.