Let say that you want to do an order confirmation that will recap the order summary as well as show the Product detail ordered.
1. Create a Message2 in Ofsys (Message2, not Message1). Put your header and footer. Each Message in Ofsys has an IdMessage, keep it.
2. Create a relational table "Order_Summary" with fields: IdContact, IdProductList, Order_summary" with fields : Order_total, Order_Number, Order_date,...
3. Create another relational table "Order_details" with fields: IdProductList, Product_name, Product_brand, Product_price, Product_color, Product_url, etc...
We'll setup a script in your Message that will link this Message with the two relational tables. When you send the Message to the idContact, the script in the Message will populate the Message with the right content based on idContact. It will draw the information corresponding to the idContact that it finds in the relational tables. You update the tables by API, and you clean them by API after usage ;-))
Advantage is that because the Message is in Ofsys, you keep fast control over layout.
Another advantage is keeping statistics because it is sent via Ofsys.