Example of an e-mail header

Below is an example of an e-mail header with an explanation about each of its sections.

  • Example of an e-mail header
  • Apparently-To, Delivered-To, and To:
  • From:
  • In-Reply-To:
  • Cc:
  • Bcc:
  • Subject:
  • Return-Path:
  • Received:
  • Message-ID:
  • Lines beginning with “X-:” in the e-mail header
  • Content-Type, Content-Transfer-Encoding, and MIME-version

Delivered-To: [email protected]Received: by 1.1.1.1 with SMTP id g2cs974866bue;Sun, 21 Jan 2007 10:40:50 -0800 (PST)Received: by 1.1.1.1 with SMTP id o6mr53068agc.11694048335;Sun, 21 Jan 2007 10:40:49 -0800 (PST)Return-Path: <[email protected]>Received: from web58308.mail.re3.yahoo.com (web58308.mail.re3.yahoo.com [1.1.1.1])by mx.computerhope.com with SMTP id 9si5512040agc.2007.01.21.10.40.48;Sun, 21 Jan 2007 10:40:49 -0800 (PST)Received-SPF: pass (computerhope.com: domain of [email protected] designates 1.1.1.1 as permitted sender)DomainKey-Status: good (test mode)Received: (computerhope 52644 invoked by uid 60001); 21 Jan 2007 18:40:48 -0000DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws;s=s1024; d=yahoo.com;h=X-YMail-OSG:Received:Date:From:Subject:To:MIME-Version:Content-Type:Content-Transfer-Encoding:Message-ID;b=efbVrw8c8wqr4eSQzCeW7649jwVofY/e5lXFywYad7Q/Tns7dS5p/OZCKCZA=;X-YMail-OSG: JF41QboVM1mJ19dW6KPDoUWVXm.95cEcw- Received: from [1.1.1.1] by web58308.mail.re3.yahoo.com via HTTP; Sun, 21 Jan 2007 10:40:48 PSTDate: Sun, 21 Jan 2007 10:40:48 -0800 (PST)From: Fake Mail <[email protected]>Subject: Re: test e-mailTo: [email protected]MIME-Version: 1.0Content-Type: multipart/related; boundary=“0-842682536-1169404848=:50690"Content-Transfer-Encoding: 8bitMessage-ID: <[email protected]>–0-842682536-1169404848=:50690Content-Type: multipart/alternative; boundary=“0-1777241646-1169404848=:50690”–0-1777241646-1169404848=:50690Content-Type: text/plain; charset=iso-8859-1Content-Transfer-Encoding: 8bit

Apparently-To, Delivered-To, and To:

The lines that begin with Delivered-To and To contain the e-mail address of who is receiving the e-mail.

The following example is only an example and may not be the same as how your e-mail program or online service displays an e-mail header.

From:

The line that begins with From is who sent the e-mail.

In-Reply-To:

Although not displayed on the example above (even though the subject contains Re:), lines beginning with In-Reply-To contain the message-id of the e-mail used for replies. Not all e-mail servers use this feature.

Cc:

The line beginning with Cc contains any e-mail address that was sent a carbon copy of the message.

Bcc:

Lines that begin with Bcc are any BCC (blind carbon copy) e-mail addresses that were also sent the e-mail. Although not all e-mail programs display this information because of privacy concerns, there are several programs that will.

Subject:

The Subject line contains the subject of the e-mail.

Return-Path:

The line beginning with Return-Path is what e-mail should be used if an error is encountered while the e-mail is being delivered.

Received:

Lines beginning with Received contain each of the mail servers that the e-mail has passed through to get to your Inbox. This section is useful in troubleshooting e-mails that are not getting to the destination because it contains the e-mail server, IP address, the date sent, and other useful information.

The Received line is also useful as an indication of who sent the e-mail. Often the first Received line (the lowest on the list) is the mail server that originated the e-mail. However, spammers can create a fake (spoof) Received entry, making it appear that an e-mail passed through their server and that their server is not the e-mail’s origin.

Message-ID:

The line starting with Message-ID is the assignment given to the e-mail message from the first e-mail server.

Lines beginning with “X-:” in the e-mail header

Lines beginning with X- are extra data that are not in any standard and used by mail servers and e-mail clients to provide information for sending e-mail. Below is a short list of some common X- lines you may see while viewing an e-mail header.

  • X-Complaints-To: - Where to direct your complaints you have about an e-mail you received.
  • X-Confirm-Reading-To: - Create an automatic response for read messages.
  • X-Errors-To: The address to send an e-mail to for any errors encountered.
  • X-Mailer: - Program used to send the e-mail.
  • X-PMFLAGS: - Additional information used with Pegasus Mail.
  • X-Priority: - Priority of sending e-mail.
  • X-Sender: - Additional information about the sender of the e-mail.
  • X-Spam-zzz: - Where zzz is any number of different spam tags relating to the Spam filter on the e-mail server. Some of these include: Checker-Version, Level, Report, and Status.
  • X-UIDL: - Used with e-mails distributed over POP.

Content-Type, Content-Transfer-Encoding, and MIME-version

Used by MIME to know how to understand and display the e-mail in the e-mail program.

  • How to view an e-mail header.
  • See the e-mail definitions for further information and related links.
  • E-mail help and support.