Re: Delivery Notifications in SMTP

[Steve Kille <[e-mail]>]

John,

I think that you have misunderstood the 1327 DR mapping.  You talk
about the basic messge mapping (e.g., some non-critical per-recipient
information is mapped onto 822 comments).

The core DR information is carried in the body of the message, where
it cannot be touched by nasty mailers!

Steve

 >From:  John C Klensin <[e-mail]>
 >To:    [e-mail]
 >Subject: Re: Delivery Notifications in SMTP
 >Date:  Tue, 05 Oct 1993 01:00:04 -0400 (EDT)

 >Steve,
 >
 >Either I'm not understanding part of the issue here, or we have a
 >rather basic misunderstanding about what is possible (maybe two).  Let's
 >hope it is the first.
 >
 >>The DR mapping in 1327 has two objectives to achieve.  
 >>
 >>1) Present the user information to the end RFC 822 user.
 >>
 >>2) Ensure that key diagnostic information is not lost.   Throwing away
 >>information in the mapping is very very bad news.   Some fields are
 >>often so much cruft, but sometimes the information is key to
 >>disgnosing a problem.
 >
 >Ok, seems reasonable.   But the mechanism used seems to involve what, to
 >822, are comment fields.  There is no 822 requirement that comment
 >fields be displayed to the user.  There is no requirement that they be
 >available to the user.  There is not even any requirement that they be
 >retained outside the sending system: a gateway, or UA-level relay, can
 >arguably simply discard them and still be in spec.
 >
 >That is a pretty poor facility on which to rely for something you
 >consider important.
 >
 >>I think that unless the new 822 format is designed with gatewaying in
 >>mind, it is unlikely that an upgraded 1327 would be able to use it
 >>effectively.
 >
 >Anything one puts in an 822 header at this point is no better than
 >advisory--even if the information is retained, a receiving system is
 >free to ignore it (and still claim conformance to 822).  MIME doesn't
 >change that, although it may change some of the social dynamic over
 >time.  Consequently, if you really want DRs, you are going to need to
 >appeal to the transport layer, where  sender can insist that the
 >receiver acknowledge support for that capability (see Keith Moore's
 >recent I-D for one such model).  
 >
 >IMHO, one of the difficulties with 1327 (and predecessors) is that it
 >collapsed both MTA and MUA (P11/P33) functions onto 822.   Since
 >competent "pure" 821/822 MTAs don't look at that information, anything
 >that involves transport or delivery-to-mailbox functionality is going to
 >get lost or screwed up all too often.
 >
 >    john
 >