Electronic face sheets are relatively cost-effective express delivery, and the cost is relatively low, ranging from a few cents to a few cents. Different courier companies are different, and different courier outlets are different. You can only ask the courier company number at the courier outlet responsible for the delivery area. But the courier company will only give you the number that can be used at that time, and the specific number is generally not given. You have to dock with the courier company, you send a package, and they will refund the bill to you. The electronic single interface can also be connected to third-party platforms such as Fast Bird, and can be connected to multiple courier companies at one time. Their interfaces are free to use, and neither SF nor Post need to find an outlet to pay the bill number. They will directly return the single number to you, but the other four links still need to pay the bill number with the outlets in advance.