Yofus.com ranked fifth on the list and fourth among personalized-printing sites.

Yinxiang pai's success is attributed to 163.com's large user base and its 1997 establishment of a Web portal. Yofus is based on the network of more than 30 digital printing branches across the country under the 22-year-old printing company, Tianyi.

"Personalized printing's e-commerce has a higher entry threshold than the traditional printed calendar industry," said Dong, Yofus' CEO.

"It requires an online shopping mall, user-friendly DIY software, quality printing technology and a network strongly connecting every business link from taking orders to printing to delivery."

He believed it is difficult for wholesale markets' relatively small calendar producers to develop such a comprehensive marketing and production chain.

"But those small printers can join big companies as production centers," Dong said.

"So they can also benefit from personalized printing's boom."