Ask most people how they determine who sent them an email message and the response is almost universally, "By the From line." Unfortunately this symptomatic of the current confusion among internet users as to where particular messages come from and who is spreading spam and viruses. The "From" header is little more than a courtesy to the person receiving the message. People spreading spam and viruses are rarely courteous. In short, if there is any question about where a particular email message came from the safe bet is to assume the "From" header is forged.
So how do you determine where a message actually came from? You have to understand how email messages are put together in order to backtrack an email message. SMTP is a text based protocol for transferring messages across the internet. A series of headers are placed in front of the data portion of the message. By examining the headers you can usually backtrack a message to the source network, sometimes the source host. A more detailed essay on reading email headers can be found .
If you are using Outlook or Outlook Express you can view the headers by right clicking on the message and selecting properties or options.
Below are listed the headers of an actual spam message I received. I've changed my email addressand the name of my server for obvious reasons. I've also double spaced the headers to make them more readable.
Return-Path: <hunkforu@yahoo.com>
X-Original-To: siddhu@example.com
Delivered-To: siddhu@example.com
Received: from 12-218-172-108.client.mchsi.com (12-218-172-108.client.mchsi.com [12.218.172.108]) by mailhost.example.com (Postfix) with SMTP id 1F9B8511C7for <siddhu@example.com>; Sun, 16 Nov 2003 09:50:37 -0800 (PST)
Received: from (HELO 0udjou) [193.12.169.0] by 12-218-172-108.client.mchsi.com with ESMTP id <536806-74276>; Sun, 16 Nov 2003 19:42:31 +0200
Message-ID: <n5-l067n7z$46-z$-n@eo2.32574>From: "Maricela Paulson" <hunkforu@yahoo.com>Reply-To: "Maricela Paulson" <hunkforu@yahoo.com>To: siddhu@example.comSubject: STOP-PAYING For Your PAY-PER-VIEW, Movie Channels, Mature Channels...ishaDate: Sun, 16 Nov 2003 19:42:31 +0200X-Mailer: Internet Mail Service (5.5.2650.21)X-Priority: 3MIME-Version: 1.0Content-Type: multipart/alternative; boundary="MIMEStream=_0+211404_90873633350646_4032088448"
According to the From header this message is from Maricela Paulson at hunkforu@yahoo.com. I could just fire off a message to abuse@yahoo.com, but that would be waste of time. This message didn't come from yahoo's email service.
The header most likely to be useful in determining the actual source of an email message is the Received header.According to the top-most Received header this message was received from the host 12-218-172-108.client.mchsi.com with the ip address of 21.218.172.108 by my server mailhost.example.com. An important item to consider is at what point in the chain does the email system become untrusted? I consider anything beyond my own email server to be an unreliable source of information. Because this header was generated by my email server it is reasonable for me to accept it at face value.
The next Received header (which is chronologically the first) shows the remote email server accepting the message from the host 0udjou with the ip 193.12.169.0. Those of you who know anything about IP will realize that that is not a valid host IP address. In addition, any hostname that ends in client.mchsi.com is unlikely to be an authorized email server. This has every sign of being a cracked client system.
Here's is where we start digging. By default Windows is somewhat lacking in network diagnostic tools; however, you can use the tools at to do your own checking. When you get the IP of the person who sent the mail, just enter the IP in geocities.com. You will know from which country or area it came up from.
So how do you determine where a message actually came from? You have to understand how email messages are put together in order to backtrack an email message. SMTP is a text based protocol for transferring messages across the internet. A series of headers are placed in front of the data portion of the message. By examining the headers you can usually backtrack a message to the source network, sometimes the source host. A more detailed essay on reading email headers can be found .
If you are using Outlook or Outlook Express you can view the headers by right clicking on the message and selecting properties or options.
Below are listed the headers of an actual spam message I received. I've changed my email addressand the name of my server for obvious reasons. I've also double spaced the headers to make them more readable.
Return-Path: <hunkforu@yahoo.com>
X-Original-To: siddhu@example.com
Delivered-To: siddhu@example.com
Received: from 12-218-172-108.client.mchsi.com (12-218-172-108.client.mchsi.com [12.218.172.108]) by mailhost.example.com (Postfix) with SMTP id 1F9B8511C7for <siddhu@example.com>; Sun, 16 Nov 2003 09:50:37 -0800 (PST)
Received: from (HELO 0udjou) [193.12.169.0] by 12-218-172-108.client.mchsi.com with ESMTP id <536806-74276>; Sun, 16 Nov 2003 19:42:31 +0200
Message-ID: <n5-l067n7z$46-z$-n@eo2.32574>From: "Maricela Paulson" <hunkforu@yahoo.com>Reply-To: "Maricela Paulson" <hunkforu@yahoo.com>To: siddhu@example.comSubject: STOP-PAYING For Your PAY-PER-VIEW, Movie Channels, Mature Channels...ishaDate: Sun, 16 Nov 2003 19:42:31 +0200X-Mailer: Internet Mail Service (5.5.2650.21)X-Priority: 3MIME-Version: 1.0Content-Type: multipart/alternative; boundary="MIMEStream=_0+211404_90873633350646_4032088448"
According to the From header this message is from Maricela Paulson at hunkforu@yahoo.com. I could just fire off a message to abuse@yahoo.com, but that would be waste of time. This message didn't come from yahoo's email service.
The header most likely to be useful in determining the actual source of an email message is the Received header.According to the top-most Received header this message was received from the host 12-218-172-108.client.mchsi.com with the ip address of 21.218.172.108 by my server mailhost.example.com. An important item to consider is at what point in the chain does the email system become untrusted? I consider anything beyond my own email server to be an unreliable source of information. Because this header was generated by my email server it is reasonable for me to accept it at face value.
The next Received header (which is chronologically the first) shows the remote email server accepting the message from the host 0udjou with the ip 193.12.169.0. Those of you who know anything about IP will realize that that is not a valid host IP address. In addition, any hostname that ends in client.mchsi.com is unlikely to be an authorized email server. This has every sign of being a cracked client system.
Here's is where we start digging. By default Windows is somewhat lacking in network diagnostic tools; however, you can use the tools at to do your own checking. When you get the IP of the person who sent the mail, just enter the IP in geocities.com. You will know from which country or area it came up from.
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