Send an email notification when custom order status changes in WooCommerce

Question

I have created a custom order status in my WooCommerce called Back Order (wc-backorder):

/**
     * Add custom status to orde         


        

Answer 1

add_action("woocommerce_order_status_changed", "my_custom_notification");

function my_custom_notification($order_id, $checkout=null) {
   global $woocommerce;
   $order = new WC_Order( $order_id );
   if($order->status === 'backorder' ) {
      // Create a mailer
      $mailer = $woocommerce->mailer();

      $message_body = __( 'Hello world!!!' );

      $message = $mailer->wrap_message(
        // Message head and message body.
        sprintf( __( 'Order %s received' ), $order->get_order_number() ), $message_body );

      // Cliente email, email subject and message.
     $mailer->send( $order->billing_email, sprintf( __( 'Order %s received' ), $order->get_order_number() ), $message );
     }

   }

Try this