Skip to content
EntityQ300851· pop 16· linked from 67 articles

X.400 is a suite of ITU-T recommendations that define the ITU-T Message Handling System (MHS).

~14 min read

Encyclopedic overview

11 sections
Contents
  • History
  • Implementation
  • Addressing
  • X.500 directories
  • See also
  • Notes
  • References
  • General references
  • Further reading
  • ITU-T X.400 Recommendations
  • External links

X.400 is a suite of ITU-T recommendations that define the ITU-T Message Handling System (MHS).

At one time, the designers of X.400 expected it to be the predominant form of email, but this role has been taken by SMTP-based Internet e-mail. Despite this, it has been widely used within organizations and was a core part of Microsoft Exchange Server until 2006; variants continue to be important in military and aviation contexts.

Excerpted from Wikipedia’s “X.400” article, available under the CC BY-SA 4.0 licence.