protected function unsubscribeDifference($listId, array $subscribers)
    {
        $mailchimpEmails = $this->listRepository->getSubscriberEmails($listId);
        $internalEmails = array_map(function (Subscriber $subscriber) {
            return $subscriber->getEmail();
        }, $subscribers);

        // emails that are present in mailchimp but not internally should be unsubscribed
        $diffenceEmails = array_diff($mailchimpEmails, $internalEmails);
        if (sizeof($diffenceEmails) == 0) {
            return;
        }

        $this->listRepository->batchUnsubscribe($listId, $diffenceEmails);
    }