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

1629	 *1630	 * @param int|null $result     The site ID if the site name exists, null otherwise.1631	 * @param string   $domain     Domain to be checked.1632	 * @param string   $path       Path to be checked.1633	 * @param int      $network_id Network ID. Only relevant on multi-network installations.1634	 */1635	return apply_filters( 'domain_exists', $result, $domain, $path, $network_id );1636}1637 1638/**1639 * Notifies the site administrator that their site activation was successful.1640 *1641 * Filter {@see 'wpmu_welcome_notification'} to disable or bypass.