trackback( string $trackback_url, string $title, string $excerpt, int $ID )

function trackback($trackback_url, $title, $excerpt, $ID) {
	global $wpdb;

	if ( empty($trackback_url) )
		return;

	$options = array();
	$options['timeout'] = 10;
	$options['body'] = array(
		'title' => $title,
		'url' => get_permalink($ID),
		'blog_name' => get_option('blogname'),
		'excerpt' => $excerpt
	);

	$response = wp_safe_remote_post( $trackback_url, $options );

	if ( is_wp_error( $response ) )
		return;

	$wpdb->query( $wpdb->prepare("UPDATE $wpdb->posts SET pinged = CONCAT(pinged, '\n', %s) WHERE ID = %d", $trackback_url, $ID) );
	return $wpdb->query( $wpdb->prepare("UPDATE $wpdb->posts SET to_ping = TRIM(REPLACE(to_ping, %s, '')) WHERE ID = %d", $trackback_url, $ID) );
}