If the application documents are mailed, they shall be sent by registered mail. If you can't send it by registered mail, you can use express mail instead of parcel. In addition to indicating the detailed address of the Patent Office or its agency (including postal code), the registered letter should also indicate the words "application documents", "China National Intellectual Property Administration Patent Office accepted" or "China National Intellectual Property Administration Patent Office accepted". It is best not to submit the application documents through the courier company, but through the courier company, with the actual date of receipt of the application documents by the patent office and its agents as the application date. The registered letter shall only contain the application documents or other documents of the same application. After mailing, the applicant shall properly keep the registered receipt stub.