Zhang Yanjiang, a veteran courier, said during the shopping festival the quantity of packages doubles, and delivery workers have to put in overtime to meet targets.

Zhang has worked for STO Express, a major express delivery company, for 11 years. On Singles Day, he usually starts work at 5 am and finishes at around 10 pm, compared with 6 am to 8 pm on regular days.

The shifts worked by couriers, and speeding to make deliveries on time, have been issues in the media spotlight recently.

Zhang said conflicts between couriers and customers were inevitable, especially when a delivery worker is new to an area. However, when a courier gets to know the community and households better, misunderstandings are minimized, he said.

The country has about 4 million couriers.