can anyone tell what is meaning of the following e-mail source? field by field?

Question

From
Return-Path:
X-Sender:
X-Apparently-To:
Received: (qmail 75816 invoked from network); 13 Jul 2006 09:07:04 -0000
Received: from unknown (ip address)
by m31.grp.scd.yahoo.com with QMQP; 13 Jul 2006 09:07:04 -0000
Received: from unknown (HELO web26901.mail.ukl.yahoo.com) (217.146.176.90)
by mta3.grp.scd.yahoo.com with SMTP; 13 Jul 2006 09:07:03 -0000
Received: (qmail 96132 invoked by uid 60001); 13 Jul 2006 09:05:49 -0000
Message-ID: <20060713090549.96130.qmail@.....
Received: from [ip address] by web26901.mail.ukl.yahoo.com via HTTP; Thu, 13 Jul 2006 10:05:49 BST
Date: Thu, 13 Jul 2006 10:05:49 +0100 (BST)
To:
In-Reply-To:
MIME-Version: 1.0
Content-Type: multipart/alternative; boundary="0-780260216-11527815...
Content-Transfer-Encoding: 8bit
X-Originating-IP:
X-eGroups-Msg-Info: 1:0:0:0
From:

Answer 1

Recieved: Start at the bottom one.
Message-ID: <20060713090549.96130.qmail@.....
Received: from [ip address] by web26901.mail.ukl.yahoo.com via HTTP; Thu, 13 Jul 2006 10:05:49 BST
The first server recieves the email from HTTP meaning a web based email. It is sent via the server web26901.mail.ukl.yahoo.com, the originators ip address is in this bottom Recieved line. Received: from [ip address] by web26901.mail.ukl.yahoo.com via HTTP; Thu, 13 Jul 2006 10:05:49 BST
The rest of the recieved lines above this is the path from server to server of the email to get to your server which is on this line.
Received: (qmail 75816 invoked from network); 13 Jul 2006 09:07:04 -0000
Received: from unknown (ip address)
by m31.grp.scd.yahoo.com with QMQP; 13 Jul 2006 09:07:04 -0000
The Messege-ID line is a way to track back the messege, yahoo can do this if you were to give them that messege id but you cannot.
Date: Thu, 13 Jul 2006 10:05:49 +0100 (BST)
is the original date of the email, from the source.
To: Who the email was sent to.
In-Reply-To: If you have a different reply to address defined it is listed here.
These 3 lines
MIME-Version: 1.0
Content-Type: multipart/alternative; boundary="0-780260216-11527815...
Content-Transfer-Encoding: 8bit
deal with how the messege is encoded by the email originator's client. Email is encoded usually in a MIME version to prevent different servers along the way from getting confused on how to handle it. Since windows and linux, and unix machines handle end of lines and carriage returns differently this prevents them from getting scrambled.
X-Originating-IP: Originating IP if available.

The meat of the messege is the the recieved to:'s , they start with the last server they touch before they get to your email client then go back in time and server they touch to the originator.