Source : Free On-Line Dictionary of Computing

Message Handling System
     
         (MHS) The {standard} defined by {ITU-T}
        as {X.400} and by {ISO} as {Message-Oriented Text Interchange
        Standard} (MOTIS).  MHS is the X.400 family of services and
        {protocol}s that provides the functions for global {electronic
        mail} transfer among local mail systems and {MTA}s.
     
        It is used by {CompuServe}, among others.
     
        (1996-09-25)