东西已经邮寄出 通过查tracking发现对方已经has been successfully delivered三天了 但一直没有收到邮件 看了一下网站的信息
If you have returned your parcel using Recorded Delivery or another service that can be tracked, please give us the reference number when you contact us.
想问下这个reference number是指什么 tracking no.吗
谢谢