Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!orion.oac.uci.edu!ucivax!gateway
From: pcl@pegasus.att.COM
Newsgroups: comp.protocols.iso.x400
Subject: Re: X.400 Questions
Message-ID: <9103261527.aa23691@ICS.UCI.EDU>
Date: 26 Mar 91 23:32:48 GMT
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Will,

In regard to your question to "mhsnews" about email service providers
using X.400 as a gateway to other providers and how that gets reflected
in the user interface - I can explain a bit of what we do in AT&T Mail
(now part of AT&T EasyLink Services).  We do use X.400 to gateway
with (many!) other service providers (other ADMDs), as well as to
connect to some of our customers who operate PRMDs.  It is a gateway,
in that we do have our own (ASCII-based) message header format within
our network, but we also give our users a way of entering O/R addresses
when sending mail out to users in other domains.  We give them a way
of abbreviating X.400 domain names into a single token, but they can
also spell out the complete O/R address if they choose - with either
form, they just have to prefix the address with "mhs!" to indicate that
it is to go through the X.400 gateway (in keeping with our general use
of UUCP-style addresses).  So a (fictional) example address that shows
the syntax for sending to a PRMD user is the following:

	mhs!/C=GR/AD=attmail/PD=Mt.Olympus/PN=Athena

("GR" is the ISO 3166 country code for Greece.
"AD" => ADMD; "PD" => PRMD; and "PN" => Personal Name;
all of this predates by several years the currently emerging
standards on visual representation of O/R addresses.)

Or, if I were originating this on a UNIX (r) system that is linked into
AT&T Mail, I would just prefix it with "attmail!" to get it to the AT&T
Mail service:

	attmail!mhs!/C=GR/AD=attmail/PD=Mt.Olympus/PN=Athena

If there were such a PRMD, we might establish "olympus" as the
abbreviated name for it, the use of which would simplify the above
address to:

	attmail!mhs!olympus/PN=Athena

(These domain abbreviations are only usable, and only visible, within
our network, of course - what goes across the X.400 link is the
standard O/R address form.)

Similarly, each of our users has an O/R address, the most complete form
of which includes the user's unique user-ID.  So my O/R address is

	/C=US/AD=attmail/PN=Paul_Lustgarten/DD.ID=plustgarten

("DD.ID" => the "ID" DDA; we use "_" for spaces separating the
components of a name)

If the name happens to be unique within our customer population (as
mine is), the DDA can be omitted and our gateway will still map the
O/R address into the appropriate user-ID, using our regular customer-
directory capabilities (which are available to any on-line users of our
service).

As you can see, this doesn't entail much administration
of individual names or addresses at the gateway!


	Paul Lustgarten			908-576-2928
	AT&T EasyLink Services		plustgarten@attmail.COM