The unnamed man, from China's eastern Shandong province, died after taking delivery of a box of shoes in late November which were tainted with methyl fluoroacetate, a highly toxic chemical, the Xinhua news agency reported citing the local post bureau.
The bureau said four parcels delivered by Shanghai YTO Express, a private delivery company, were found to be contaminated by the chemicals, sickening five delivery workers and two recipients. The report did not state the condition of the injured.
Xinhua said YTO had apologised for the accident and quoted a spokesman saying that the contamination occurred after a package containing the toxic chemical leaked during transport.
The company said the package was sent by a chemical plant in central China's Hubei province who claimed it was "innoxious".
The spokesman was quoted as saying the delivery company staff had performed routine checks "according to company rules" and that it would cooperate with an ongoing police investigation.
Chinese citizens are often angered by their country's poor safety record amid regular industrial accidents, health scares and contaminations.
Chinese parents became particularly distrustful of domestic milk brands after a huge 2008 scandal involving formula tainted with melamine that killed six children and sickened 300,000 others.
Their concern triggered a rush on milk powder, which saw shelves emptied around the world -- Hong Kong banned travellers taking out more than 1.8 kilogrammes of formula from March 1 this year.
The safety of medicines is another key area where Chinese citizens have concerns.
Recent scandals include drug capsules made from toxic raw material derived from scrap leather and the busting of a ring peddling counterfeit tablets.
In 2008 a blood thinner called heparin, produced in China, was found to be contaminated and linked to dozens of deaths.
Xinhua said the country's private delivery network was "one of China's fastest growing industries" but added experts said the sector was beset with problems like "poor service and lax supervision".