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Re: Maybe simple question

2003-12-14 12:41:07
On Saturday 13 December 2003 01:58 pm, Wechsler wrote:
marrandy wrote:

OK - so's I understand this -
MUA from == mail message 'from'
MTA from == mail envelope 'from'


Wechsler.

When you look at a 'normal'  mail in your mailer (MUA), in your case
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.5) Gecko/20030925

You will see something like this (taking your spf-discuss list message as an 
example :--

Subject: Re: [spf-discuss] Maybe simple question
From: Wechsler <wechsler(_at_)phase(_dot_)org>
To: spf-discuss(_at_)v2(_dot_)listbox(_dot_)com
Date: Yesterday 01:58:31 pm

But when you look at the logs of a SMTP session on an MTA, you will see this 
:-

Trying 212.13.198.241...
Connected to heifong.phase.org (212.13.198.241).
Escape character is '^]'.
220 heifong.phase.org ESMTP Exim 3.35 #1 Sun, 14 Dec 2003 19:29:38 +0000
ehlo v2.listbox.com
250-heifong.phase.org Hello perm76-1.ij.net [209.216.76.1]
250-SIZE
250-PIPELINING
250 HELP
MAIL FROM: owner-spf-discuss(_at_)v2(_dot_)listbox(_dot_)com
250 <owner-spf-discuss(_at_)v2(_dot_)listbox(_dot_)com> is syntactically correct
RCPT TO: Wechsler <wechsler(_at_)phase(_dot_)org>
250 <wechsler(_at_)phase(_dot_)org> verified
data
354 Enter message, ending with "." on a line by itself

....etc



Note the  MAIL FROM: owner-spf-discuss(_at_)v2(_dot_)listbox(_dot_)com

This is the MTA it is claimed to be from.  Any problems (e.g. user unknown,  
over quota etc.) will have a return (bounce) sent to that address.

If you look at all headers in your MUA, you will see :-

Return-Path: <owner-spf-discuss(_at_)v2(_dot_)listbox(_dot_)com>

So what has happened, is the MTA receiving the mail, has saved the part 
MAIL FROM: owner-spf-discuss(_at_)v2(_dot_)listbox(_dot_)com
and added a header called Return-Path:  with
owner-spf-discuss(_at_)v2(_dot_)listbox(_dot_)com

Regards...Martin
-- 
Win98 is called Win98 because no matter how fast your computer is, Windoze
will use up 98% of the system resources for itself.

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