Visa approval letter is a document issued by the Vietnam Immigration Department that permits foreigners to enter and exit Vietnam in a given period of time. After having the visa approval letter, you can get onto your plane and receive visa upon arrival at one of the give major international airports in Vietnam (Hanoi, Hochiminh City, Da Nang, Phu Quoc and Cam Ranh).
There is one important thing you need to know that the visa approval letter is NOT acceptable for those who enter by crossing BORDERLAND or by SEAPORTS.
Note: Vietnam visa approval letter is usually issued in group and therefore, you may find some of your passport detail in the same letter as other people.
