CUSTOMERS WILL NEED TO FOLLOW NEW RULES WHEN SHIPPING CERTAIN PACKAGES. . These regulations will make it mandatory for you to list each item in your package with a "specific, accurate description" on the customs declaration form. "Acceptable goods descriptions must include complete, detailed information, explaining the precise nature of the goods in plain language," the USPS explains on its website, adding that it must also give "an indication of what the goods are, what they are made of, and what purpose they serve." The USPS says the new postal regulations apply to nearly 30 countries.