Here are some of the most common causes of errors when trying to create a label to an international or US military address:
There are foreign characters in the customer’s address
Non-English characters may cause the address to not be recognized by the carrier. To remedy any error, click “Edit” on the Recipient Address field and replace any non-English character with the closest English equivalent - it will not affect delivery and will allow you to print the label.
The sender/recipient name field is incorrectly formatted or incomplete
USPS will return an error if the sender or recipient information is incomplete. The error typically received is "The sender address must contain a first and last name, or a company name must be added".
On international labels, the name for both the sender and the recipient address must follow a strict format of a "first name" and a "last name" and both must have more than one character. These do not have to be your actual first and last name but can be your business name. For example, instead of just "Shippo" in the first name field, "Shippo Inc." could be used to complete both fields.
The US military address is incorrectly formatted or incomplete
APO/FPO/DPO addresses can be complex and may look unfamiliar. All the information must be on the right lines and include all necessary details (box/unit numbers, etc) in order to be valid. The USPS provides a guide for how these addresses should look to be accepted in their system, which you can find on their website.
The US military address lists the wrong country/city/state
US military addresses must have "United States" as the country, and either APO, FPO, or DPO as the city. The state must be either AP, AE, or AA. Yes, these addresses may be physically located in other countries, but that's just the format of US military and diplomatic addresses.
The US military address is missing a phone number
Phone numbers are required for international shipments and shipments to military addresses. If you’re unable to move past Step 1 of label creation because the Recipient address box continues to pop up, please be sure to enter a phone number for the recipient and save the changes.
Example of a US military address in Shippo: