protected function startCollectingMailSystemMail() {
    if (\Drupal::moduleHandler()->moduleExists('mailsystem')) {
      $config = \Drupal::configFactory()->getEditable('mailsystem.settings');
      $data = $config->getRawData();

      // Track original data for restoration.
      $this->storeOriginalConfiguration('mailsystem.settings', $data);

      // Convert all of the 'senders' to the test collector.
      $data = $this->findMailSystemSenders($data);
      $config->setData($data)->save();
    }
  }