WordPress at a glance
function is not described

wpmu_log_new_registrations() WP 3.0.0

Logs the user email, IP, and registration date of a new site.

  • Global. wpdb. $wpdb WordPress database abstraction object.

No Hooks.

Return

Nothing (null).

Usage

wpmu_log_new_registrations( $blog_id, $user_id );
$blog_id(int) (required)
$user_id(int) (required)

Code of wpmu log new registrations: wp-includes/ms-functions.php VER 5.0.3

<?php
function wpmu_log_new_registrations( $blog_id, $user_id ) {
	global $wpdb;
	$user = get_userdata( (int) $user_id );
	if ( $user )
		$wpdb->insert( $wpdb->registration_log, array('email' => $user->user_email, 'IP' => preg_replace( '/[^0-9., ]/', '', wp_unslash( $_SERVER['REMOTE_ADDR'] ) ), 'blog_id' => $blog_id, 'date_registered' => current_time('mysql')) );
}