However, Hong said not all workers obey the rules, and "there were many cases of user information being leaked".

Zhang Guoquan, a manager at the Tianshuiyuan community branch of Shanghai Yunda Express in Beijing, said he also receives phone calls inquiring about sales of receipts and tracking numbers.

"I never even talk with them. I have been in this industry for more than 10 years, and I knew how important reputation is. To me it is a matter of principle," he said.

Meanwhile, another area of the industry causing concern to the authorities is the poor disposal of parcel boxes and receipts, by companies and customers.

In February, a court in Xiamen, Fujian province, sentenced a 24-year-old man to death after he was convicted of killing a woman, who attracted his attention as being wealthy because she had made so many purchases online, which arrived at her home by express delivery.

He noticed the number of parcels she had disposed of at her residential community, and the man had been using the boxes for clues about her wealth.

He then pretended to be an express delivery worker, and when she opened the door he gained entry and killed and then robbed her, according to a report by the People's Court Daily.

In a statement issued by the national postal authority on Dec 10, express delivery users are reminded to remove any receipts from the outside of any parcels and make sure they do not disclose anything about their personal information before throwing them away.

Contact the writer at xuwei@chinadaily.com.cn