There is a mail drop in the main terminal pre-security (source). Locate the Travelex; it should be across from there next to an ATM and/or “change machine”.
USPS will pick up at 5pm Monday through Friday and 1:45pm on Saturday (holidays excepted).
It’s located on the terminal map. This isn’t the most user-friendly UI out there. Select “Services” in the checkbox menu and zoom in when items show up on the map.
Robert first notified me of the location on 9/8/2017. Thanks Robert!
Last Updated 2 November 2017