Errors-to: owner-drums@CS.UTK.EDU
Message-Id: <199505312005.QAA19760@CS.UTK.EDU>
Date:        Wed, 31 May 1995 21:45:34 +0200
From: Eric Thomas <ERIC@SEARN.SUNET.SE>
Subject:     Re: getting started
To: "Perry E. Metzger" <perry@imsi.com>
cc: drums@CS.UTK.EDU
In-Reply-To: Message of Wed, 31 May 1995 15:48:06 -0400 from "Perry E. Metzger"
             <perry@imsi.com>

On Wed,  31 May 1995  15:48:06 -0400 "Perry E.  Metzger" <perry@imsi.com>
said:

>2) If  you can't  understand that this  issue is not  a unix  issue, you
>don't understand the issue.

Of course I understand that this has  nothing to do with unix. I was just
showing how ridiculous it is to  suggest that people can't gateway to the
Internet  if the  mail system  being gatewayed  to doesn't  have all  the
properties of Internet mail.

>3) I get on the order of two dozen improperly redirected bounce messages
>   per day  from brain-damaged  machines that  don't have  this properly
>   implemented.  I  really feel  all  those  people  should be  off  the
>   internet until they can fix their hardware.

Hardware??? If you can't understand that this isn't a hardware issue, you
clearly don't understand the issue.

>> It's easy  for you  to make this  kind of demand,  but there  are MANY
>> popular  mail systems  that  don't have  a concept  of  "errors go  to
>> address 1, replies go to address 2".  So you have two options. You can
>> gateway them imperfectly, or not gateway them.
>
>Do you understand the difference between MTA and MUA?

Of  course. Do  you  have any  experience with  mail  systems other  than
RFC822? You  know, mail systems  where there  is a field  called "From:",
which  is used  by  the MUA  to  show  the message  origin  in the  inbox
directory, to send replies, to send delivery receipts, and by the MTA for
delivery errors  and delivery  receipts, everything.  One size  fits all.
Well, guess  what happens when you  try to gateway this  to the Internet?
The gateway has to put *something* in the one-size-fits-all origin field.
No matter what it  uses, it will be incorrect; it  will just be incorrect
in different ways. The gateway  usually doesn't know whether the delivery
will succeed, all it can do is  pipe the message into the target network.
So, there are two options: you make  a brain damaged gateway, or you make
no gateway. Examples  of mail systems exhibiting this  problem include MS
Mail, VMSmail, All in one, PROFS/OV,  and just about any LAN mail package
you  care to  name. About,  say, 90%  of the  non-Internet/corporate mail
packages currently on  the market. Come to think about  it, the only mail
system I can think of which  can be "correctly" gatewayed to the Internet
is X.400 :-)

  Eric