I don't know if the USPS website will accurately list airports, since there isn't an exact street address for terminals.

Anyway, I would assume that mailboxes than have previously existed in airports would still exist. I happen to be in C now and the one in front of customer service/near the ATMs has moved some. Now when you come off the escalator, it is immediately to your right, near the elevator that goes down to the tunnel. I won't be making it over to F today, so I'm not sure about T2. I would guess there is one somewhere.

Edit: In B, it is also near the entrance to the tunnel, on the far edge of the Starbucks there.