What form is required for all Priority Mail International shipments?

For all Priority Mail International shipments, a Customs Declaration form is mandatory. This form serves several important functions, such as providing details about the contents of the package, their value, and the nature of the items being sent. The Customs Declaration is essential for customs clearance in the destination country, allowing authorities to assess any duties or taxes that may apply and ensuring compliance with international shipping regulations.

While the other forms mentioned may pertain to international shipping, they do not specifically encompass the comprehensive requirements needed for customs clearance. Thus, the Customs Declaration is the correct choice, as it is a standard requirement across international mail services for proper processing and delivery.