对拓展信函种类的探讨□赵宁□杭州市邮政局信函是邮政的基础业务和专营业务。从大清邮政至今，此项业务开展已有１００多年了。人类进入２０世纪后，通过对电磁波的研究，找到了新的更先进的信息载体，发明了电话、电报、电传、传真，特别是近几年来计算机的普及，汉字信... Discussion on the Development of Correspondence Types □ Zhao Ning □ Hangzhou Post Office Correspondence is the postal basic business and the franchise business. From the postal service so far, this business has been carried out more than 100 years. After entering into the 20th century, mankind has found new and more advanced information carriers through the study of electromagnetic waves, and invented telephones, telegrams, telexes and facsimiles, especially the popularization of computers in recent years.