// přidání relativních produktů do emailu o zpracovávání objednávky
add_action( 'woocommerce_email_after_order_table', 'vandaal_add_product_grid_specific_email', 20, 4 );
   
function vandaal_add_product_grid_specific_email( $order, $sent_to_admin, $plain_text, $email ) {
    
   if ( $email->id == 'customer_processing_order' ) {
       
      $related = array();
      foreach ( $order->get_items() as $item_id => $item ) {         
         $related = array_merge( wc_get_related_products( $item->get_product_id() ), $related );
      }
      if ( ! $related ) return;
      shuffle( $related );
      $related = array_unique( $related );
       
      echo '<h2>Naše další zajímavé produkty</h2>';
       
      $html = '';
      $col = 1;
      $cols = 3;
      $limit = 6;
      $html .= '<div><table style="table-layout:fixed;width:100%;"><tbody>';     
      foreach ( array_slice( $related, 0, $limit ) as $product_id ) {
         $product = wc_get_product( $product_id );
         $html .= ( $col + $cols - 1 ) % $cols === 0 ? '<tr>' : '';
         $html .= '<td style="text-align:center;vertical-align:bottom">';
         $html .= $product->get_image();
         $html .= '<h3 style="text-align:center">' . $product->get_title() . '</h3>';
         $html .= '<p>' . $product->get_price_html() . '</p>';
         $html .= '<p><a href="' . get_permalink( $product_id ) . '">' . __( 'Read more', 'woocommerce' ) . '</a></p></td>';
         $html .= $col % $cols === 0 ? '</tr>' : '';
         $col++;
      }
      $html .= '</tbody></table></div>';
       
      echo $html;
       
   }
}