Message Handling System (MHS) is an important early email protocol developed by Action Technologies, Inc. (ATI) in 1986.
A wide variety of email clients used MHS, including: 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.
A compatible family of products from Infinite Technologies (now Captaris) and marketed under the name Connect2[2] were also very widely used as part of MHS-based email networks.
At about the same time, confidence in the future of X.400 collapsed and SMTP email across the public internet became the compelling choice for mail between unrelated organisations, replacing MHS's former "glue" role.
Through the provision of fundamental messaging features and integration capabilities, these systems enable enterprises to create reliable, scalable, and effective applications that satisfy the requirements of contemporary distributed computing settings.