View e-mail message headers

E-mail message headers provide a list of technical details about the message, such as who sent it, the software used to compose it, and the e-mail servers that it passed through on its way to the recipient.

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About message headers

After you compose a message and send it, the message is processed by the e-mail server at your Internet service provider (ISP) (ISP: A business that provides access to the Internet for such things as electronic mail, chat rooms, or use of the World Wide Web. Some ISPs are multinational, offering access in many locations, while others are limited to a specific region.). If the message is for someone who does not have a mailbox on your e-mail server, the server forwards the message to another e-mail server. The message is forwarded from server to server. It may go through several e-mail servers until it reaches the e-mail server on which the recipient of the message has a mailbox.

From the time when the message is first created, information about it is added to a hidden section of the message known as the Internet header. The information includes technical details, such as who created the message, the software used to compose it, and the e-mail servers it passed through on its way to the recipient. You can use these details to identify problems with the e-mail message or help discover the sources of unsolicited commercial e-mail messages.

 Note   The practice of providing false information in message headers is a growing problem. This is also known as spoofing. For example, a message might indicate that it is from Eric Lang at Alpine Ski House (eric@alpineskihouse.com) when it is actually from a bulk e-mail service that promotes schemes to get rich quickly. Therefore, before you send an angry reply to someone complaining about his or her message, remember that the header information might be forged.

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View message headers

  1. Open a message.
  2. On the Message tab, in the Options group, click the Dialog Box Laucher Icon image.

In the Message Options dialog box, the headers appear in the Internet headers box.

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Contents of e-mail headers

Consider an e-mail exchange between two people, Anton Kirilov and Kelly J. Weadock. Anton's e-mail address is anton@proseware.com and Kelly's address is kelly@litwareinc.com. Kelly uses Microsoft Office Outlook 2007. The Internet header associated with Kelly's message to Anton looks as follows:

Microsoft Mail Internet Headers Version 2.0
Received: from mail.litwareinc.com ([10.54.108.101]) by mail.proseware.com with Microsoft SMTPSVC(6.0.3790.0);
Wed, 12 Dec 2007 13:39:22 -0800
Received: from mail ([10.54.108.23] RDNS failed) by mail.litware.com with Microsoft SMTPSVC(6.0.3790.0);
Wed, 12 Dec 2007 13:38:49 -0800
From: "Kelly J. Weadock" <kelly@litware.com>
To: <anton@proseware.com>
Cc: <tim@cpandl.com>
Subject: Review of staff assignments
Date: Wed, 12 Dec 2007 13:38:31 -0800
MIME-Version: 1.0
Content-Type: multipart/mixed;
X-Mailer: Microsoft Office Outlook, Build 12.0.4210
X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165
Thread-Index: AcON3CInEwkfLOQsQGeK8VCv3M+ipA==
Return-Path: kelly@litware.com
Message-ID: <MAILbbnewS5TqCRL00000013@mail.litware.com>
X-OriginalArrivalTime: 12 Dec 2007 21:38:50.0145 (UTC)

 Note   The sample header might not contain all items found in your e-mail headers. These are the most common entries.

When Kelly sends an e-mail message to anton@proseware.com, she composes it from her computer, which is identified as (i101-177.nv.litwareinc.com). The composed text is passed from her computer to the e-mail server, mail.litwareinc.com. This is the last that Kelly will see of her e-mail message, because further processing is handled by e-mail servers with no intervention from her. When Kelly's e-mail server receives the message for anton@proseware.com, it contacts Proseware's e-mail server and delivers the message to it. The message is stored on the proseware.com server until Anton checks his Proseware e-mail messages.

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Common fields in e-mail headers

The following is an explanation of the common e-mail header fields:

Microsoft Mail Internet Headers Version 2.0

This header is added by Outlook.

Received: from mail.litwareinc.com ([10.54.108.101]) by mail.proseware.com with Microsoft SMTPSVC(6.0.3790.0);
Wed, 12 Dec 2007 13:39:22 -0800

This information says that the message transfer occurred on Wednesday, December 12, 2007, at 13:39:22 (1:39:22 in the afternoon) Pacific Standard Time (which is 8 hours later than Coordinated Universal Time (Greenwich Mean Time); thus the "–0800").

Received: from mail ([10.54.108.23] RDNS failed) by mail.litware.com with Microsoft SMTPSVC(6.0.3790.0);
Wed, 12 Dec 2007 13:38:49 -0800

This message transfer occurred on Wednesday, December 12, 2007, at 13:38:49 (1:38:49 in the afternoon) Pacific Standard Time (which is 8 hours later than Coordinated Universal Time (UTC); thus the "–0800").

From: "Kelly J. Weadock" <kelly@litware.com>

This message was sent by Kelly J. Weadock from the e-mail address kelly@litware.com.

To: <anton@proseware.com>

This is the person to whom the e-mail message is addressed.

Cc: <tim@cpandl.com>

These are the person or persons who receive carbon copies of the message.

 Note   Recipients of blind carbon copies (Bcc) do not appear in the header.

Subject: Review of staff assignments

This is the subject of the e-mail message.

Date: Wed, 12 Dec 2007 13:38:31 -0800

This indicates the date and time that the e-mail message was sent, based upon the computer clock on the sender's computer.

MIME-Version: 1.0

This parameter specifies the version of the MIME protocol that was used by the sender.

Content-Type: multipart/mixed;

This is an additional MIME header. It tells MIME-compliant e-mail programs about the type of content to expect in the message.

X-Mailer: Microsoft Office Outlook, Build 12.0.4210

This information indicates that the message was sent by using Microsoft Office Outlook with a build version of 12.0.4210.

X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165

This entry indicates the e-mail software (MIME OLE software) used by the sender.

Thread-Index: AcON3CInEwkfLOQsQGeK8VCv3M+ipA==

This header is used to associate multiple messages with a similar thread. For example, in Outlook, the conversation view uses this information to find messages from the same conversation thread.

Return-Path: kelly@litware.com

This entry specifies how to reach the message sender.

Message-ID: <MAILbbnewS5TqCRL00000013@mail.litware.com>

The message has been assigned this number by mail.litware.com for identification purposes. This ID will always be associated with the message.

X-OriginalArrivalTime: 12 Dec 2007 21:38:50.0145 (UTC)

This is a time stamp placed on the message when it first passes through a server running Microsoft Exchange.

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Applies to:
Outlook 2007