Question:
The messenger receipt is not showing when I configure the checkout fields setting to have the ZIP code as “Hidden”. However, if ZIP field has value, then Messenger Receipt is auto generated. It seems for the Messenger Receipt to generate, the ZIP code is being considered to have a value.
Answer:
Unfortunately, the Postal ID or Zip code is required by Facebook for Messenger Receipts. If a customer does not input a zip code, then Facebook will not send the Messenger receipt.