How to Interpret Email Headers
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Extended
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Sample "extended" email header Return-Path: general@leestreet.com Received: from mailmule0.leestreet.com (mailmule0.leestreet.com [204.180.128.191]) by mailgrunt1.leestreet.com (8.7.4/8.7.3) with ESMTP id TAA09377 for <mailbox@leestreet.com>; Mon, 24 Feb 2004 19:30:43 -0500 (EST) Received: from LOCALNAME (user-37kb512.dialup.leestreet.com [207.69.148.34]) by mailmule0.leestreet.com (8.8.4/8.8.4) with SMTP id TAA00875; Mon, 24 Feb 2004 19:30:34 -0500 (EST) Date: Mon, 24 Feb 2004 19:30:34 -0500 (EST) Message-Id: 1.5.4.16.19970224193529.22e79a46@pop.leestreet.com X-Sender: mailbox@pop.leestreet.com X-Mailer: Windows Eudora Light Version 1.5.4 (16) Organization: Lee Street Management Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: leesvr.com Management Technical Support Group <support@leesvr.com> From: mailbox@leestreet.com Subject: Reading Mail Headers Cc: mailbox@leestreet.com Return-Path: mailbox@leestreet.com Your email client will automatically refer to this header line to determine which address to use when replying, or by the mail server when bouncing back undeliverable mail messages or mailer-daemon error messages. Some mail clients will use variations which might include: Return-Errors-To: or Reply-To: Received: frommailmule0.leestreet.com (mailmule0.leestreet.com [204.180.128.191]) bymailgrunt1.leestreet.com (8.7.4/8.7.3) with ESMTP id TAA09377 for mailbox@leestreet.com; Mon, 24 Feb 2004 19:30:43 -0500 (EST) A section is added to this field by each host service that relays the message. Received: lines are read from bottom to top, the higher received lines being the most recent to have been added. While not terribly interesting to the casual user, the information in the Received: field can be quite useful for tracing mail routing problems. The names of the sending and receiving hosts and time-of-receipt may be specified. The example above shows four pieces of useful information (reading from back to front, in order of decreasing reliability):
In short, mailmule0.leestreet.com passed the mail on to mailgrunt1.leestreet.com for final delivery to <mailbox@leestreet.com> at approximately 5:30 pm EST on Monday, February 24th. Received: from LOCALNAME (user-37kb512.dialup.leestreet.com [207.69.148.34]) by mailmule0.leestreet.com (8.8.4/8.8.4) with SMTP id TAA00875; Mon, 24 Feb 2004 19:30:34 -0500 (EST) This is actually the first Received: line. It indicates that the mail message originated from a Lee Street dial-up PPP account with IP address 207.69.148.34. The mail server that eventually accepted the message was mailmule0.leestreet.com , which was using SendMail version 8.8.4, a UNIX mail delivery agent. The mail server also stamped the header with the actual time it received the message. Note that the time indicated is a few seconds before the header line above it. Organization: Lee Street Management This line is used to identify the organization (or lack there of!) of the sender. Typically the default configuration for your mail settings is going to be "Lee Street Management" but you can easily change this to something more personal to your family or specific to your business. Message-Id: 1.5.4.16.19970224193529.22e79a46@pop.leestreet.com Every mail message is assigned a unique Message-Id which helps your email client, as well as mail server, to keep track of the status of a message, and thought it looks like an email address, it really isn't. Generally this information is of no use to you and only matters to the mail server. For example, if you have Eudora configured to leave a copy of your email on the mail server, the next time you check your mail, your email client will first compare the message id's to determine if it has already seen a message, and if it should download another copy of it or just skip it. Message-Id's are also logged in special mail logs which can be called on by your system administrators (in this case "postmasters") when trying to troubleshoot technical issues like mail loops or forged mail messages. X-Sender: mailbox@pop.leestreet.com Some email clients will include a X-Sender header to add another layer of authentication to a mail message. In the example, Eudora uses information supplied in its configurations settings. X- headers may be thought of as "X-tra" information and are more or less X-traneous comments. They do not impact the normal delivery process of the mail. X-Mailer: Windows Eudora Light Version 1.5.4 (16) Some email clients will add this header line to indicate the make and version of the software used to send the message. In this case, the mailer used was the 16 bit version 1.5.4 of Eudora Light for Windows, the email client Lee Street Management currently uses with its software. If I had sent the mail from Netscape's Mozilla mail program, the X-Mailer might have looked something like this: X-Mailer: Mozilla 3.01 (Win95; I) Not all email clients include an X-Mailer header. Mime-Version: 1.0 MIME-compatible email clients look for this line when first determining what to do with attachment files-- if MIME attachments are included, email clients first be sure they understand compatible MIME types. For those of you obsessed with acronyms, MIME stands for Multipurpose Internet Mail Extensions. It is an Internet standard for transferring non-textual data through email. MIME is what makes it possible to exchange graphic documents and multimedia files across systems. Content-Type: text/plain;charset="us-ascii" This line tells the receiving email client exactly what MIME type or types are included in the mail message. As long as the MIME-type referenced is compatible with the mail program it should have no problems automatically decoding the attachments. In the example above, [text/plain; charset="us-ascii"] just tells us that the message contains a regular ASCII text message. |