An approval letter and photos are required documents of visa application for Vietnam airport. If you forget to bring those documents, you need to pay extra money (2-5 USD) to get your photos taken by Immigration Officers & a lot of money to print out the Arrival Letter right there.
We recommend you use our Airport Pickup (aka Fast Track) service to ensure you can enter Vietnam quickly and conveniently. Please contact us via the hotline +84 if you have any difficulties entering Vietnam airport.