@Override
 public String addSubscription() {
   try {
     String mailAddress = this.getMailAddress();
     INewsletterManager newsletterManager = this.getNewsletterManager();
     Subscriber subscriber = newsletterManager.loadSubscriber(mailAddress);
     if (subscriber == null) {
       newsletterManager.addSubscriber(mailAddress);
     } else if (!subscriber.isActive()) {
       newsletterManager.resetSubscriber(mailAddress);
     } else {
       return INPUT;
     }
   } catch (Throwable t) {
     ApsSystemUtils.logThrowable(
         t, this, "addSubscription", "Errore durante l'aggiunta di una sottoscrizione");
     return FAILURE;
   }
   return SUCCESS;
 }