Nothing on their Web site.
Robert mentions a blue collection box:
Blue mailbox next to Sky Gallery restrooms in atrium prior to security.
The airport map is an abomination – but it looks like Sky Gallery is on the left as you first enter the atrium.
A better locator is the information kiosk as the first thing you pass in the center of the atrium. Stand in front, then look left. The bathrooms should be visible. Walk towards the bathrooms and start looking around. If you can’t find it, ask at the information counter.
Google Maps indicates a business center right in that area too.
Collection time is 11am every postal business day.
Last Updated 21 November 2021