newuser_notify_siteadmin() WordPress Function

function newuser_notify_siteadmin( $user_id ) {
	if ( 'yes' !== get_site_option( 'registrationnotification' ) ) {
		return false;
	}

	$email = get_site_option( 'admin_email' );

	if ( is_email( $email ) == false ) {
		return false;
	}

	$user = get_userdata( $user_id );

	$options_site_url = esc_url( network_admin_url( 'settings.php' ) );

	$msg = sprintf(
		/* translators: New user notification email. 1: User login, 2: User IP address, 3: URL to Network Settings screen. */
		__(
			'New User: %1$s
Remote IP address: %2$s

Disable these notifications: %3$s'
		),
		$user->user_login,
		wp_unslash( $_SERVER['REMOTE_ADDR'] ),
		$options_site_url
	);

	/**
	 * Filters the message body of the new user activation email sent
	 * to the network administrator.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param string  $msg  Email body.
	 * @param WP_User $user WP_User instance of the new user.
	 */
	$msg = apply_filters( 'newuser_notify_siteadmin', $msg, $user );

	/* translators: New user notification email subject. %s: User login. */
	wp_mail( $email, sprintf( __( 'New User Registration: %s' ), $user->user_login ), $msg );

	return true;
}