When shipping a First-Class International envelope or large envelope with 'Documents' selected as the content type, it is required that only valueless documents be shipped. Beginning on 1/21/2018 you may be presented with a mail fraud warning that you need to agree to before processing this type of shipment.
You will only need to agree to the warning one time for each USPS or Endicia account you use to process this type of shipment. Check the box for I certify, under penalty of Federal mail fraud, that the label to be printed will be used only to send valueless documents, then click the Agree and Continue button.
Clicking Cancel will display the following dialog.