You can't. According to the Interim Provisions on Administrative Punishment or Disciplinary Action for Violating Foreign Exchange Control Regulations, such as fraudulent purchase of foreign exchange, illegal arbitrage, evasion of foreign exchange, and illegal trading of foreign exchange, foreign currency cannot be sent by express mail. The legal basis is: Article 29 of the Measures for the Administration of Express Delivery Market. No organization or individual may use the express delivery service network to engage in activities that endanger national security, social interests or the legitimate rights and interests of others.