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From: JPALME@qz.qz.se (Jacob Palme QZ)
Newsgroups: comp.protocols.iso.x400
Subject: Re: Need Comparison Of X.400 And SMTP
Message-ID: <670446*JPALME@QZ.qz.se>
Date: 26 Mar 91 09:54:54 GMT
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X400-Received: by /PRMD=QZ/ADMD=TEDE/C=SE/; Relayed; 26 Mar 91 10:44:10+0100

Answers to some questions I have received:

(1) The advantage with standardized formats for delivery
and non-delivery notifications is that the UA software can
recognize these automatically, and handle them in the
manner you want. The way this is to be done is not fully
standardized, since X.400 is mainly a standard for the
interchange of information between local systems, not a
standard for how these local systems should work internally.

(2) By tracing and loop control I mean that you add a log to
a message of what has happended during its transmission (which
domains it has passed etc) so that if by error the same message
goes around and comes back to the same domain once more, it
will be stopped and not looping around indefinitely.

(3) Of course the RFC821/822 type of mail handling could be
extended with all the features where X.400 at present has
advantages. However, one should first discuss what is best,
to convert to X.400 or to extend RFC821/822 with more features!
The advantage with converting to X.400 is that we will at
some time in the future avoid the problem of two different
standards, with problems of gatewaying etc. Of course I
understand that RFC821/822 style mail will continue to live
for a long time even if it will gradually be phased out and
replaced by X.400.

At the very least, if RFC821/822 is to be extended with new
features similar to those in X.400, this should be done in
a manner which is highly compatible with how X.400 does the
same thing.

(4) More information about X.400 handling of distriubtion
lists can be found in F.400(1988) or in MOTIS (ISO 10021) part
1. That part is an introduction to X.400/MOTIS, it contains a
fairly good description of distribution list handling in X.400.