How can someone with an X.400 mailer address send mail to an IU address?

X.400 users should consult their own computing support center first. At Indiana University, which uses an internet mail address in the form of, there are two alternatives for an X.400 address. The correct one depends on whether or not the sender's X.400 mail system has defined mapping:

  • If there is defined mapping onto standard attributes for a domain, then the following address:
    maps to:
      C=no;ADMD= ;PRMD=uninett;O=sintef;OU=delab;S=Alvestrand;G=Harald
  • If there is no such mapping, a Domain Defined Attribute (DDA) must be used, where this address:
    maps to:
      <Std. Attributes of a gateway>;DD.RFC-822=Someone(a)

An Internet Engineering Task Force (IETF) working document (draft-ietf-x400ops-mgtdomains-01.txt) suggests using C=us;ADMD= ;PRMD=Internet to mean "any gateway to the Internet". This might not be supported on some X.400 services, or some commercial services.

The following characters have special conversion rules when used in DDAs:

This character: Converts to:
@ (at sign) (a)
! (exclamation point) (b)
% (percent sign) (p)
_ (underscore) (u)

For more, see the IETF's RFC 1327.

For gateways that do not conform to RFC 987, RFC 1148, or RFC 1327, all bets are off. For instance, the kindest description of the result of passing through the gateways of most commercial X.400 service providers is "interesting".


A bug exists that causes mail addressed to "/..../@gateway" to fail. Typically, the error message reads:

  << /...../@gateway: Cannot mail directly to files

This is document aaxa in the Knowledge Base.
Last modified on 2018-05-14 11:28:00.

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