Xu Hua sends a letter to his 6-year-old son, who will receive it when he is 18. In the slow delivery, Xu told his son to grow up to be a man willing to help others. Zou Hong / China Daily

It is common for people to compare the slow delivery service of China Post with Panda Slow Post, a privately run delivery service in the 798 Art Zone.

But staff at Hujialou Post Office believe the difference is credibility.

"China Post has its credibility and brand. Customers can have confidence that the letters they hand to us will be delivered. But as to the privately operated services, it is difficult to say whether they will still be in business the day the letter is meant to be delivered," said Sun Yang, a deputy director at Hujialou Post Office.

"Some people wonder whether we are copying the idea from Panda Post. Actually the idea was introduced during the 2008 Olympics. People wrote postcards to memorize their feelings during the grand gathering," said Sun.

The slow post at Hujialou began around five in the afternoon on Feb 10, explained Gao Hui, who works at the post and received the very first business of slow mail.

"A 40-year-old man asked us to deliver a later to his son in 12 years time, when reaches 18." "We were greatly moved by his love for his son. We were thrilled to complete the first business of slow delivery in our post office," said Gao.

In the following two days, another two customers came into the post office requesting slow delivery. "We can see that all three letters will be delivered to the customers' relatives, or the people they are closest to. So we think this business is very sentimental," added Gao.

Hei Xiaoqian, another member of staff at the post office said she herself is thinking of writing a letter to her children."When they heard of my idea, they just burst into 'Do it right away'," said Hei. "I think it is a very romantic idea indeed."

Each letter costs 3.8 yuan for delivery only. Another 10 yuan will be charged for storage for the first year. After that, the price goes down to five yuan a year. The letters remain in the care of the Beijing Commerce Security Bureau.

The business is called "The letter written for the future", and only letters are accepted as yet.

"As the business is relatively small at present, delivering letters is the only service," said Xu Yao, deputy director of the Hujialou Post Office.