Many new cross-border sellers will encounter hidden fees, cargo detention and delayed compensation disputes when shipping to Europe, USA and Mexico. Today we summarize four core screening standards to help you select formal and stable DDP suppliers. First, confirm that the quotation is fully inclusive. Standard DDP costs should cover domestic pickup, sea/air freight, export declaration, destination customs clearance, tariff, VAT and last-mile delivery, without any additional surcharges. Second, verify the clearance capacity for sensitive goods. If you ship batteries, cosmetics and liquids to Mexico, the supplier must have local stable customs channels to avoid long-term detention leading to inventory loss. Third, check the maximum limit of oversized cargo. Regular suppliers can accept irregular goods up to 6m / 3 tons with professional wooden frame reinforcement protection. Fourth, confirm the written delay compensation rule. Reliable logistics providers will clearly mark 0.5 RMB per KG per working day compensation in official cooperation contracts.