How to send email to candidate when resume is approved?

 
    function resume_published_send_email($post_id) {
        $post = get_post($post_id);
        $author = get_userdata($post->post_author);
     
        $message = "
           Hi ".$author->display_name.",
           Your resume, ".$post->post_title." has just been approved at ".get_permalink( $post_id ).". Well done!
        ";
        wp_mail($author->user_email, "Your resume is online", $message);
     }
     add_action('publish_resume', 'resume_published_send_email');