Looooong header of this list

Why this list has such a looooooooooong header (or whatever you call it)?
It traveles travels multiplies multiplies and often is longer than a mail
itself. What is the reason for it? Does everybody reads carefully abd
always these lines?
Greetings
Henryk Gajewski

Example:

Resent-Date: Mon, 11 May 1998 07:18:46 -0400 (EDT)
Date: Mon, 11 May 1998 07:10:45 -0400 (EDT)
Old-X-Envelope-From: www-html-request@www10.w3.org  Mon May 11 07:10:44 1998
X-Authentication-Warning: www10.w3.org: Host ns.datadesign.se
[194.23.109.130] claimed to be sussie.datadesign.se
To: rys@tir.com
Cc: www-html@w3.org
Cc: kaj@interbizz.se
From: Rasmus Kaj <kaj@interbizz.se>
X-URL: http://www.e.kth.se/~kaj/
X-Attribution: kaj
Mime-Version: 1.0
Old-Date: Mon, 11 May 1998 13:10:36 +0200
X-Dispatcher: imput version 971024
Lines: 31
Old-X-Envelope-To: www-html
Subject: Re: HTML Includes
Resent-From: www-html@w3.org
X-Mailing-List: <www-html@w3.org> archive/latest/172
X-Loop: www-html@w3.org
Sender: www-html-request@w3.org
Resent-Sender: www-html-request@w3.org
Precedence: list
Status: N

Received on Monday, 11 May 1998 13:30:33 UTC