Add email attachment for certain product only

add-email-attachments-for-certain-product.php

add_filter( 'woocommerce_email_attachments', 'add_woocommerce_attachments_for_certain_product', 10, 3 );

function add_woocommerce_attachments_for_certain_product ( $attachments, $email_id, $email_order ){
  $product_id = 217762;
  $attachment_id = 217944;

  if( $email_id === 'customer_processing_order' ){
	$order = wc_get_order( $email_order );
    $items = $order->get_items();
  
    foreach ( $items as $item ) {
      if ( $product_id === $item->get_product_id() ) {
		$attachments[] = get_attached_file( $attachment_id );		
	  }
    }	 
	
  }
  return $attachments;
}