The letter paper, the envelopes and the stamps are just as important as the other contents because they can send different messages, he says.

His recipients include former teachers whose addresses he has made a point of keeping, especially for occasions such as Teachers' Day.

Ma Ben of Hangzhou, Zhejiang province, says she started writing letters when she was an undergraduate student in Nanjing, under the influence of her Australian English-language teacher, himself a keen advocate of letter writing.

Later when she studied in Britain in 2012 she was surprised to find that sending letters or postcards was still popular there, especially during festivals.

"The pretty stamps in Britain were additional attractions for me. So I started to write more letters, and have kept that up with friends since I returned home."

She is keen for each letter she writes to be unique, and that includes spraying them with perfume, changing writing styles or including a little gift. The importance of putting in that extra effort is clear when she herself receives a letter.

"When an envelope finally reaches me after traveling from afar it immediately lifts my spirits."