Post office in JFK
 

The airport website says the following:
JFK offers a full-service post office which is located at Building 250, on North Boundary Road

does anyone happen to know whether there are mailboxes within any of the airport terminals?
Thanks!

I may be wrong but I don't think there are any mailboxes inside the terminals any more for security reasons. I remember when I was flying out of JFK 2 years ago I had some postcards I wanted to post and I asked in the lounge where I could post them and the girl told me they didn't have boxes in the terminals anymore. She very kindly took them for me and posted them on her way home. Someone one else may know more.

I agree. I do not think that there are any mailboxes in the departure terminals of JFK. I do not believe that the post office is located within the departure/arrival terminals. I do not know where Building 250. There are 8 terminals at JFK. I think that I have been all 8 of them.

There is a mailbox in Terminal 8. It is outside security, along the walkway from the AirTrain to the checkin location - right near some elevators.

I do not recall seeing (nor was I looking for) any mailboxes inside the secure area.

Just mailed my letters from Terminal 4 at jfk, arrivals floor.

There were no mailboxes; I asked people and they showed me this place which provides postal service. I had my own stamps, they accepted my letters at no charge. It is not a regular post office, and they probably only accept letters, and not parcels.