I'm having a stupidly hard time finding postcards and stamps in Manila -- it looks like postal mail has been comprehensively obsoleted here by SMS!
Can I find postcards, stamps and a mailbox to send them off at Manila Ninoy Aquino Airport? Terminals 1 or 3, to be specific, either landside or airside.
Post Office
The NAIA Terminal 2 Post Office is located at the South Wing of the Arrival Lobby beside the Pass Control Office
Post Box
Located within the area of the Post Office, accessible even on weekends.
Pick-up Schedule Monday to Friday: 10:30AM
Stamps
Postage stamps are sold by retail shops near Gate 1 of the South Wing Pre-departure Hall and infront of the Philippine Airlines Business Class Counter, Check-in Hall of the North Wing. These shops are authorized by the Philippine Postal Corp. These shops are authorized by the Philippine Postal Corp.
Business Hours Daily: 5:00AM to 9:00PM
According to the Philippine Postal Corporation website, no postal offices are available at Manila Airport. Likewise checking the airport map for all four terminals failed to find anything related to postal services.
However there are plenty of postal offices in downtown Manila, so perhaps you could try your luck there next time.
