ITU-T X.400 PDF

This Recommendation defines the overall system and service of an MHS and serves as a general overview of MHS.

Other aspects of message handling systems and services are defined in other Recommendations. The layout of Recommendations defining the message handling system and services is shown in Table 1. The public services built on MHS, as well as access to and from the MHS for public services are defined in the F.400-series Recommendations.

The technical aspects of MHS are defined in the X.400-series Recommendations. The overall system architecture of MHS is defined in ITU-T Rec. X.402 | ISO/IEC 10021-2