protected function findMailSystemSenders(array $data) {
    foreach ($data as $key => $values) {
      if (is_array($values)) {
        if (isset($values[MailsystemManager::MAILSYSTEM_TYPE_SENDING])) {
          $data[$key][MailsystemManager::MAILSYSTEM_TYPE_SENDING] = 'test_mail_collector';
        }
        else {
          $data[$key] = $this->findMailSystemSenders($values);
        }
      }
    }
    return $data;
  }