ISO/IEC 10021 is the ISOstandard which defines the overall system and service of an Information technology - Message Handling Systems (MHS) and serves as a general overview of Message Handling Systems.
Other aspects of Message Handling Systems and Services are defined in other parts of ISO/IEC 10021. The structure of ISO/IEC 10021 (all parts) defining the Message Handling System and Services is given in Table 1.
The technical aspects of MHS are defined in other parts of ISO/IEC 10021. The overall system architecture of MHS is defined in ISO/IEC 10021-2:1996.