public function formatMailChimp()
    {
        $options = $this->options;
        if (!empty($this->getMergeFields())) {
            $options = array_merge([
                'merge_fields' => $this->getMergeFields()
            ], $options);
        }

        return array_merge([
            'email_address' => $this->getEmail()
        ], $options);
    }