What is confidential express?

Secret Express: The deliveryman doesn't need to know what's inside. The consignee who is delivering the goods already knows that even if the consignee doesn't know, if it is transported by air or train, the transportation department must check the delivery, but if it is contraband, it cannot be delivered. In the delivery man's hands, all he has to do is deliver the goods to the customers.

2.

Contains important documents or related personal items, and has certain privacy elements.

It was all sent in secret!