Trigger email on new CPT

add_action('draft_to_publish' ,'send_emails_on_new_event');

function send_emails_on_new_event($post)
{
    if(get_post_type($post->ID) === 'ttshowcase')
    {

    $emails = get_option('admin_email');
    $title = wp_strip_all_tags(get_the_title($post->ID));
    $url = get_permalink($post->ID);
    $message = "Link to testimonial single page: \n{$url}";

    wp_mail($emails, "New testimonial published: {$title}", $message);
    }
}