17. A system for serving an electronic message and its associated attachments in response to client requests, comprising: memory; a processor; and at least one program, stored in the memory and executed by the processor, the at least one program including: instructions for generating an electronic message in response to a client request from a client computer, the electronic message including an attachment viewing link corresponding to an attachment associated with the electronic message; the attachment having a document type; instructions for converting the attachment into a converted document in response to an attachment viewing request corresponding to a single user action consisting of selection of the attachment viewing link, the converted document having a document type different from the document type of the attachment; and instructions for receiving the requests from the client computer and transferring the requested electronic message and the converted document to the client computer.
17. A system for serving an electronic message and its associated attachments in response to client requests, comprising: memory; a processor; and at least one program, stored in the memory and executed by the processor, the at least one program including: instructions for generating an electronic message in response to a client request from a client computer, the electronic message including an attachment viewing link corresponding to an attachment associated with the electronic message; the attachment having a document type; instructions for converting the attachment into a converted document in response to an attachment viewing request corresponding to a single user action consisting of selection of the attachment viewing link, the converted document having a document type different from the document type of the attachment; and instructions for receiving the requests from the client computer and transferring the requested electronic message and the converted document to the client computer. 19. The system of claim 17 , wherein the attachment has a document type selected from the set consisting of a word processing document type, a spreadsheet document type, a presentation document type, and a portable document type.