apply_filters( 'domain_exists', int|null $result, string $domain, string $path, int $network_id )

1572	 *1573	 * @param int|null $result     The site ID if the site name exists, null otherwise.1574	 * @param string   $domain     Domain to be checked.1575	 * @param string   $path       Path to be checked.1576	 * @param int      $network_id Network ID. Only relevant on multi-network installations.1577	 */1578	return apply_filters( 'domain_exists', $result, $domain, $path, $network_id );1579}1580 1581/**1582 * Notifies the site administrator that their site activation was successful.1583 *1584 * Filter {@see 'wpmu_welcome_notification'} to disable or bypass.