MHS was a very 'open' system, and this, with Novell's encouragement, made it popular in the early 1990s as a 'glue' between not only the proprietary email systems of the day such as PROFS, SNADS, MCI, 3+Mail, cc:Mail, Para-Mail and Microsoft Mail, but also the competing standards-based SMTP and X.400.
operating system | Super Nintendo Entertainment System | Nintendo Entertainment System | Android (operating system) | Global Positioning System | Solar System | X Window System | Korean Broadcasting System | System of a Down | Domain Name System | Seoul Broadcasting System | North Carolina Community College System | Mutual Broadcasting System | Bulletin board system | system | Turner Broadcasting System | Program and System Information Protocol | Geographic information system | Ubuntu (operating system) | Tokyo Broadcasting System | Federal Reserve System | Youth system | Embedded system | solar system | Seigneurial system of New France | Interstate Highway System | Internet Message Access Protocol | Fedora (operating system) | Trans-Alaska Pipeline System | Network File System (protocol) |
Isode has a set of X.400 products that it classifies as both a Military Message Handling System (MMHS) and an Aviation Message Handling System (AMHS).