The reason one has a pos system is to do tasks like this. The reception side should generate its own codes and track them for safety and to keep duplicates etc from happening. (that is if you are not using your own codes from an e-card etc)

Also, there is an issue with having no 'To:' section of the card. Once a card has been given, it belongs to the new person. You run a sticky situation if the person who bought it uses it before the person they gave it to. You should add a section for the gift receiver.