Message-Id: <199710272129.QAA00172@spot.cs.utk.edu>
From: Keith Moore <moore@cs.utk.edu>
To: "Alain Zahm" <zahm@sophia.sema.fr>
cc: "Jamie Zawinski" <jwz@netscape.com>, "Graham Klyne" <GK@acm.org>,
        drums@cs.utk.edu, moore@cs.utk.edu
Subject: Re: Can different messages have the same Message-ID 
In-reply-to: Your message of "Mon, 27 Oct 1997 14:01:06 +0100."
             <199710271318.OAA09728@sema.fr> 
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Date: Mon, 27 Oct 1997 16:29:36 -0500
Sender: moore@cs.utk.edu

The answer is simple:  it is out of scope for DRUMS to define this.
There has never been support for per-message billing in Internet mail.

If you depend on message-id for billing, someone will duplicate
message-ids to get by without paying.  If you suppress messages with
duplicate id's, that creates a nice hole for denial of service attacks
-- if I know that a particular message with a particular message-id is
being sent to you, I can send you a different message with the same id
and perhaps prevent you from getting the original message.

Keith


> When I want to propose a commercial service for email where I charge
> customers on a per-message basis. I would like to show a detailed bill
> where each message is clearly identified. When my service is used as a
> relay, I want to be able to charge remote server that use my facilities.
> Each mail is store in order to have a complete track of the activity and
> find a message if any sender or recipient complain.
> 
> What is the best information to rely on ?
> 	-Date? several machine have not their date and time correctly set
> 	-Subject? many mails share the same subject.
> 
> I believe Message-Id would be a nice mean to distinguish between severa
> mails. Then standard should not allow two messages to share the same ID, in
> any case.
> 
> What is an identifier that does not allow message identification?
> 
>