public static function blockEmail($email_str, $should_update_db = true)
 {
     $params = explode(self::SEPARATOR, $email_str);
     $email = @$params[0];
     $email_hash = @$params[1];
     $valid = kString::verifyExpiryHash($email, self::$key, $email_hash, self::EXPIRY_INTERVAL);
     if ($valid) {
         if ($should_update_db) {
             try {
                 $blocked_email = new blockedEmail();
                 $blocked_email->setEmail($email);
                 $blocked_email->save();
             } catch (PropelException $pe) {
                 // already exists -  think it's better than to query the DB every time to see if the object exists or not
                 // before updating it
             }
         }
     } else {
         // hashing is wrong !
     }
     return $valid;
 }