function wpmu_signup_blog_notification( $domain, $path, $title, $user_login, $user_email, $key, $meta = array() ) {
  
/**
 * Filters whether to bypass the new site email notification.
 *
 * @since MU (3.0.0)
 *
 * @param string|false $domain     Site domain, or false to prevent the email from sending.
 * @param string       $path       Site path.
 * @param string       $title      Site title.
 * @param string       $user_login User login name.
 * @param string       $user_email User email address.
 * @param string       $key        Activation key created in wpmu_signup_blog().
 * @param array        $meta       Signup meta data. By default, contains the requested privacy setting and lang_id.
 */
  if ( ! apply_filters( 'wpmu_signup_blog_notification', $domain, $path, $title, $user_login, $user_email, $key, $meta ) ) {
    return false;
  }

  // Send email with activation link.
  if ( ! is_subdomain_install() || get_current_network_id() != 1 ) {
    $activate_url = network_site_url( "wp-activate.php?key=$key" );
  } else {
    $activate_url = "http://{$domain}{$path}wp-activate.php?key=$key"; // @todo Use *_url() API.
  }

  $activate_url = esc_url( $activate_url );

  $admin_email = get_site_option( 'admin_email' );

  if ( '' === $admin_email ) {
    $admin_email = 'support@' . wp_parse_url( network_home_url(), PHP_URL_HOST );
  }

  $from_name       = ( '' !== get_site_option( 'site_name' ) ) ? esc_html( get_site_option( 'site_name' ) ) : 'WordPress';
  $message_headers = "From: \"{$from_name}\" <{$admin_email}>\n" . 'Content-Type: text/plain; charset="' . get_option( 'blog_charset' ) . "\"\n";

  $user            = get_user_by( 'login', $user_login );
  $switched_locale = $user && switch_to_user_locale( $user->ID );

  $message = sprintf(
    
/**
 * Filters the message content of the new blog notification email.
 *
 * Content should be formatted for transmission via wp_mail().
 *
 * @since MU (3.0.0)
 *
 * @param string $content    Content of the notification email.
 * @param string $domain     Site domain.
 * @param string $path       Site path.
 * @param string $title      Site title.
 * @param string $user_login User login name.
 * @param string $user_email User email address.
 * @param string $key        Activation key created in wpmu_signup_blog().
 * @param array  $meta       Signup meta data. By default, contains the requested privacy setting and lang_id.
 */
    apply_filters(
      'wpmu_signup_blog_notification_email',
      /* translators: New site notification email. 1: Activation URL, 2: New site URL. */
      __( "To activate your site, please click the following link:\n\n%1\$s\n\nAfter you activate, you will receive *another email* with your login.\n\nAfter you activate, you can visit your site here:\n\n%2\$s" ),
      $domain,
      $path,
      $title,
      $user_login,
      $user_email,
      $key,
      $meta
    ),
    $activate_url,
    esc_url( "http://{$domain}{$path}" ),
    $key
  );

  $subject = sprintf(
    
/**
 * Filters the subject of the new blog notification email.
 *
 * @since MU (3.0.0)
 *
 * @param string $subject    Subject of the notification email.
 * @param string $domain     Site domain.
 * @param string $path       Site path.
 * @param string $title      Site title.
 * @param string $user_login User login name.
 * @param string $user_email User email address.
 * @param string $key        Activation key created in wpmu_signup_blog().
 * @param array  $meta       Signup meta data. By default, contains the requested privacy setting and lang_id.
 */
    apply_filters(
      'wpmu_signup_blog_notification_subject',
      /* translators: New site notification email subject. 1: Network title, 2: New site URL. */
      _x( '[%1$s] Activate %2$s', 'New site notification email subject' ),
      $domain,
      $path,
      $title,