I believe the email you mentioned as " 要求付钱的邮件" is titled "vPOSTUSA Shipment Alert".
You will receive shipement alert from vPost for EVERY package only after it is processed. Sometimes you may find the package is received by vPost but it uaually takes 1-2 more days for them to match and process. After processing, they will send you shipment alert letting you know the weight, etc but just ignore it if you have other packages to consolidate.