Context is: trade term. An international commercial term (Incoterm), meaning "delivered duty unpaid," that is used in international sales contracts to signify that the seller is responsible for all risks and costs incurred to have goods delivered to a named destination in the country of importation. This includes the obligation to contract and pay for freight and transportation costs, export licensing fees, and other taxes (unless specifically excluded in the contract). The buyer is responsible for obtaining import licensing, carrying out the customs formalities necessary for the importation of the goods, and paying any import duties on the goods. See also CFR; CIF; CIP; CPT; DAF; DDP; DEQ; DES; EXW; FAS; FCA; FOB; Incoterms.
A delivery unit is a post office, post office station, or post office branch that has mail delivery functions. The DDU rate is a rate available for Periodicals and Standard Mail that is properly prepared and entered by the mailer at the delivery unit that serves the delivery address on the mail.