The disclosed E-mail system comprises: a server, including a user proxy module with a Web Service container, a mail transmission proxy module, and a mail distribution proxy module; and a client. Wherein, the Web Service container comprises a main package sub-module, a mail transmission sub-module, a mail receiving sub-module, a mail decomposition sub-module, a user key management sub-module, an enciphering/deciphering sub-module, and some corresponding calling interfaces. This invention avoids repeated development, and has wide application, such as PC, palm PC, and mobile phone.