10. An electronic message system in which a plurality of users can post messages and the user refers to the posted messages, comprising: a client for transmitting a message or a request from the user; and a server for processing the message or request transmitted from said client through a network, wherein said server comprises a database which registers a plurality of kinds of message types which have previously been defined, a message inputted to said client, and a posted message in a case where said message is a message according to said posted message, and summary forming means which merges a plurality of specified related messages on a basis of information for related subject of said message types and each of the posted messages and which forms a summary by leaving at least one duplicated message among duplicated portions where the messages continue among the series of merged messages and by deleting others.
10. An electronic message system in which a plurality of users can post messages and the user refers to the posted messages, comprising: a client for transmitting a message or a request from the user; and a server for processing the message or request transmitted from said client through a network, wherein said server comprises a database which registers a plurality of kinds of message types which have previously been defined, a message inputted to said client, and a posted message in a case where said message is a message according to said posted message, and summary forming means which merges a plurality of specified related messages on a basis of information for related subject of said message types and each of the posted messages and which forms a summary by leaving at least one duplicated message among duplicated portions where the messages continue among the series of merged messages and by deleting others. 11. A system according to claim 10, wherein said server discriminates a conclusion message of a discussion by said message type and specifies a series of messages concerning a message which poses the discussion from said conclusion message by using said information for related subject.