Understanding Mail Header

An email will gather together information from each of the computers it passes through on the way to the recipient and this is stored in the email header. In Outlook, right click on the email message and select Options. (Sample as image below):

Headers are best read from the bottom up, as they are added to as the email passes through the system:

Note: The "Reply-To" field is added by the originator and serves to direct replies, whereas the "Return-Path" field is used to identify a path back to the originator.

Header line Meaning
Microsoft Mail Internet Headers Version 2.0 Header title
Received: from EXIC1.lse.ac.uk ([]) by ExF2.lse.ac.uk with Microsoft SMTPSVC(5.0.2195.5329);
Tue, 15 Jul 2003 12:16:56 +0100
Email passed from Exchange gateway servers to staff mailbox server
Received: from EXAV2.pc.lse.ac.uk ([]) by EXIC1.lse.ac.uk with Microsoft SMTPSVC(5.0.2195.5329);

Tue, 15 Jul 2003 12:16:55 +0100

Email passed from anti-virus servers to Exchange gateway server
Received: From exas1.lse.ac.uk ([]) by EXAV2.pc.lse.ac.uk (WebShield SMTP v4.5 MR1a);

id 1058267813844; Tue, 15 Jul 2003 12:16:53 +0100

Email passed from anti-spam servers to anti-virus servers
Content-Class: urn:content-classes:message  
X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4910.0300  
Received: from web60003.mail.yahoo.com ([]) by exas1.lse.ac.uk with Microsoft SMTPSVC(5.0.2195.5329); Tue, 15 Jul 2003 12:14:24 +0100

Message-ID: <20030715111424.6388.qmail@web60003.mail.yahoo.com>

Email received by LSE anti-spam server from originator's email server. This is the point of entry to the LSE.
Received: from [] by web60003.mail.yahoo.com via HTTP; Tue, 15 Jul 2003 12:14:24 BST Date and time received by the originator's email servers
Date: Tue, 15 Jul 2003 12:14:24 +0100 (BST) Date and time sent
From: "Daniel Simpson" <djs@yahoo.co.uk> Originator's email address
Reply-To: <d.simpson@hotmail.com> Reply to address
Subject: Test Email Subject
To: <f.muir@lse.ac.uk> Recipients email address
MIME-Version: 1.0  
Content-Type: multipart/alternative;  
Content-Transfer-Encoding: 8bit  
Return-Path: <djs@yahoo.co.uk> Originator's email address
X-OriginalArrivalTime: 15 Jul 2003 11:14:24.0580 (UTC) FILETIME=[3F7D6840:01C34AC2] Arrival time at originators email servers
Content-Type: text/plain;
Content-Transfer-Encoding: 7bit
Content-Type: text/html;
Content-Transfer-Encoding: 7bit
Start of the email message

To view E-Mail Header for Windows Live Hotmail/MSN, GMail, Yahoo! Mail and Outlook Express, please refer to article as below.

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