public function AddContacts($listName, $rule = null, array $emails = array(), $allContacts = false) {
        return $this->sendRequest('list/addcontacts', array(
                    'listName' => $listName,
                    'rule' => $rule,
                    'emails' => (count($emails) === 0) ? null : join(';', $emails),
                    'allContacts' => $allContacts
        ));
    }