he is so worried about me, but who is he?

Just a note, the “Delivery man” here usually work for express post companies (such as “FedEx” in a western context). The most famous express post companies in China are “Shun Feng 顺丰” (best quality), “EMS”, “Shen Tong 申通”, “Yuan Tong 圆通” etc. We all know Taobao & Alibaba in China has a huge business but nothing can be done without the support of these express delivery companies. They are extremely fast and delivery guys’ services are usually top-notch. They usually build 1:1 personal relationship with the recipients. Here is another joke about express delivery in China: Express Delivery FTW.