How does Mailpac work? 1.When you open an account with us, you are given a US mailing address or "Smart Address," which consists of a Post Office Box AND a street address. This address will become your personal address in the US and should be used as the shipping address for all online orders. 2. When the package reaches our mailing facility, we transport your packages to Jamaica. 3. Upon arrival in Jamaica we handle the customs processing. 4. When your package is at our facility you will get a notification that it is here, from there you can either have your package delivered to you, or can pick up from one of our locations.