Zeng Jinlan, who works in a beauty salon in Nanchang, Jiangxi province, is another of those who swears by the power of the handwritten word.

She often writes to her regular customers on the occasion of festivals to express her gratitude, she says, sometimes mentioning something they have experienced together.

Some customers return the thanks and post pictures of her notes on their WeChat moments page.

Her letters have also helped to melt the ice with some customers with whom she did not quite see eye to eye, she says.

On Taobao, the online shopping platform, many sellers are also taking advantage of the power of traditional letters to win loyalty and favorable reviews from customers.

Many buyers who come across a handwritten letter with a parcel they receive say how much they appreciate it.

Ma Lele, a Taobao user, says he was surprised recently when he found a red envelope containing five yuan and a long handwritten note of thanks with a parcel from a Taobao shop.

"I couldn't believe that the first letter I received after all these years was from a Taobao seller, and I was very touched. There are few chances to write, or receive, letters nowadays, and I think people miss that time when people dealt with each other through letters and handwritten words."