How to read mail header

Reading email headers can be a bit technical, but it's a useful skill to have, especially when troubleshooting email issues or trying to understand how an email was routed. Here's a breakdown of how to read an email header:

What is an email header?

An email header is the part of an email message that contains metadata, such as the sender's and recipient's email addresses, the date and time the email was sent, and information about the email's route through the internet.

Breaking down an email header

An email header typically consists of several lines, each starting with a colon and a space. Each line is called a "header field" or "header line." Here are some common header fields you might see:

  1. From: The sender's email address.
  2. To: The recipient's email address.
  3. Subject: The subject line of the email.
  4. Date: The date and time the email was sent.
  5. Message-ID: A unique identifier for the email message.
  6. Received: Information about the email's route through the internet, including the IP addresses of the servers that handled the email.
  7. Sender: The sender's email address (may be different from the "From" field).
  8. Reply-To: The email address to which replies should be sent.
  9. Return-Path: The email address to which bounces or errors should be sent.

How to read an email header

To read an email header, follow these steps:

  1. Open your email client (e.g., Gmail, Outlook, Apple Mail).
  2. Find the email you want to view the header for.
  3. Click on the "View" or "Details" button to open the email's header.
  4. Look for the "Header" or "Raw Message" section, which may be hidden by default. You may need to click on a "Show Raw Message" or "Show Header" button to reveal it.
  5. The header will be displayed in a text format, with each line starting with a colon and a space.
  6. Look for the header fields you're interested in, such as the "From," "To," "Subject," and "Received" fields.
  7. Pay attention to the order of the header fields, as they may provide clues about the email's route and handling.

Example email header

Here's an example email header:

From: [email protected]
To: [email protected]
Subject: Test email
Date: Wed, 12 Jan 2022 14:30:00 +0000
Message-ID: <[email protected]>
Received: from mail.example.com (mail.example.com [192.0.2.1])
    by mx.google.com with SMTP; Wed, 12 Jan 2022 14:30:00 +0000
Received: from localhost (localhost [127.0.0.1])
    by mail.example.com (Postfix) with ESMTP id 1234567890;
    Wed, 12 Jan 2022 14:30:00 +0000
Sender: [email protected]
Reply-To: [email protected]
Return-Path: [email protected]

In this example, we can see the sender's and recipient's email addresses, the subject line, the date and time the email was sent, and information about the email's route through the internet (the "Received" fields).