Staff members with a postal delivery company prepare packages in Yiwu, Zhejiang province. A Chinese express courier, Yuantong Express, may lose clients after media reports that personal information about its customers was sold online. Zhang Jiancheng / for China Daily

Postal delivery company Yuantong Express could face falling customer numbers after media reports that personal information on the company's express envelopes is being peddled on the Internet.

"We're concerned about the security of our personal information after the scandal with the company, so we're considering changing to another express courier," said Wang Yan, who works in the administration department of Xizi Otis Elevators, a customer of Yuantong since 2009.

Several companies have already reported switching from Yuantong, including Shanghai Jinxing, which is based in the Pudong New Area and whose main business is the import and export of wood products.

"But other express couriers may have the same problem, so we're thinking of opting for a safer method," said Cheng Pinyi, administration director of the company, which used to send about 100 packages through Yuantong on a daily basis.

Shanghai Morning Post reported on Tuesday that nearly 1 million items of personal information have been stolen and sold through the Internet, mainly through Taobao, a popular online marketplace.

The information includes the names, addresses, and cellphone numbers of both senders and recipients, all of which typically appear on the courier envelopes.

"The incident exposes external and internal loopholes in information management. We're in close cooperation with the police and Taobao to find the source of the leak of the information," said a manager with the information department of Yuantong Express who gave only his surname, Zhou.

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