public function toArray($notifiable)
    {
        return [
            'subject'     => $this->subject,
            'content'     => $this->content,
            'link'        => $this->link,
            'link_label'  => $this->link_label,
            'data'        => $this->data,
            'template'    => $this->template,
            'cc'          => $this->cc,
            'bcc'         => $this->bcc,
            'attachments' => $this->attachments,
        ];
    }