Also: I cannot figure out the Indonesian postal system. Seriously, what the hell? I went to a post office proper in Denpasar and got stamps for some postcards. Without question or options, I paid Rp. 25,000 (US$2.78) for postcard postage going to the US.
And then I sent a bunch out from the Sukarno-Hatta Airport in Jakarta, Java. The convenience store from which I bought the stamps again insisted I needed even less postage--Rp. 5,000--but also tacked on a 100% fee for each stamp! So what is the legal rate? I have no idea, but if you're in Indonesia, I strongly urge you to deal with a proper post office rather than any other service.
I never actually used this Bangkok mailbox, I'm just including it because I take pictures of mailboxes in other countries. I thought it interesting that the front of it differentiates between "Bangkok" and "Other Places." Tells you something about the mindset of a city, like how California and New York like to dismiss everything between them as "flyover states."