Validation takes place before you check in your luggage (in the departure hall)
2 types of validation :
Electronic: find a self-service kiosk (PABLO in France) and present the barcode to be scanned.
Stamp: If the kiosks do not work or if you are leaving Europe through a country other than France, you must find a customs office and present your printed document to a customs officer so that he/she can stamp it, then send it back to us.