usps notice 123

usps notice 123 is a published document by the United States Postal Service detailing all domestic and international rates, surcharges, and mailing standards. It’s an essential reference for fulfillment professionals and e-commerce businesses. Staying updated on Notice 123 helps calculate accurate shipping costs, avoid billing surprises, and apply appropriate postage. Fulfillment centers integrate this data into shipping software to automate rate selection and ensure compliance with USPS requirements across various classes of mail.