How to inquire about things by ordinary mail?

Let the sender take his ID card to the post office where the parcel is mailed, and tell the staff the name, mobile phone number and delivery address of the recipient.

Precautions for sending packages:

When mailing a parcel, registered letter or express delivery, take a photo of the single number with your mobile phone and save it, or write down the single number on the receipt and send it to the recipient by SMS after mailing. In this way, even if your receipt is lost, as long as you have this number, you can prove that you are one of the recipients/senders, and you can make a normal inquiry or complain about the delay of the package.