Mail a Postcard at Post Office

We walked through International Post Center at 6 Dinh Tien Hoang, just beside Hoan Kiem Lake. I decided to mail a postcard back to Singapore to myself. There were postcards on sold in post office, however, only when I was about to leave only got people to man the counter. So I bought a stack of 10 postcards for VND 25,000 (Expensive!) from street sellers that roamed around looking for 'prey'.

The postage to Singapore was cheap, only VND 7,000. I was not sure it's air mailed or surface mailed though, as the postcard only reached me 1 month later.