private void unsubscribeAll(String email, String key) {
   email = email.toLowerCase();
   Set<Subscription> subscriptions = subscriptionDao.getSubscriptionsBySubscribersEmail(email);
   if (subscriptions.isEmpty()) {
     log.debug(email, "is not subscribed to anything");
     return;
   }
   for (Subscription subscription : subscriptions) {
     subscription.removeSubscribersEmail(email);
   }
   log.info(email, "unsubscribed from", subscriptions.size(), "entities");
 }