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function wpmu_new_site_admin_notification( $site_id, $user_id ) {
	$site  = get_site( $site_id );
	$user  = get_userdata( $user_id );
	$email = get_site_option( 'admin_email' );

	if ( ! $site || ! $user || ! $email ) {
		return false;
	}

	/**
	 * Filters whether to send an email to the Multisite network administrator when a new site is created.
	 *
	 * Return false to disable sending the email.
	 *
	 * @since 5.6.0
	 *
	 * @param bool    $send Whether to send the email.
	 * @param WP_Site $site Site object of the new site.
	 * @param WP_User $user User object of the administrator of the new site.
	 */
	if ( ! apply_filters( 'send_new_site_email', true, $site, $user ) ) {
		return false;
	}

	$switched_locale = false;
	$network_admin   = get_user_by( 'email', $email );

	if ( $network_admin ) {
		// If the network admin email address corresponds to a user, switch to their locale.
		$switched_locale = switch_to_user_locale( $network_admin->ID );
	} else {
		// Otherwise switch to the locale of the current site.
		$switched_locale = switch_to_locale( get_locale() );
	}

	$subject = sprintf(
		/* translators: New site notification email subject. %s: Network title. */
		__( '[%s] New Site Created' ),
		get_network()->site_name
	);

	$message = sprintf(
		/* translators: New site notification email. 1: User login, 2: Site URL, 3: Site title. */
		__(
			'New site created by %1$s

Address: %2$s
Name: %3$s'
		),
		$user->user_login,
		get_site_url( $site->id ),
		get_blog_option( $site->id, 'blogname' )
	);

	$header = sprintf(
		'From: "%1$s" <%2$s>',
		_x( 'Site Admin', 'email "From" field' ),
		$email
	);

	$new_site_email = array(
		'to'      => $email,
		'subject' => $subject,
		'message' => $message,
		'headers' => $header,
	);

	/**
	 * Filters the content of the email sent to the Multisite network administrator when a new site is created.
	 *
	 * Content should be formatted for transmission via wp_mail().
	 *
	 * @since 5.6.0
	 *
	 * @param array $new_site_email {
	 *     Used to build wp_mail().
	 *
	 *     @type string $to      The email address of the recipient.
	 *     @type string $subject The subject of the email.
	 *     @type string $message The content of the email.
	 *     @type string $headers Headers.
	 * }
	 * @param WP_Site $site         Site object of the new site.
	 * @param WP_User $user         User object of the administrator of the new site.
	 */
	$new_site_email = apply_filters( 'new_site_email', $new_site_email, $site, $user );

	wp_mail(
		$new_site_email['to'],
		wp_specialchars_decode( $new_site_email['subject'] ),
		$new_site_email['message'],
		$new_site_email['headers']
	);

	if ( $switched_locale ) {
		restore_previous_locale();
	}

	return true;
}