Decode email header

A fascinating topic!

Email headers are a crucial part of an email message, containing metadata that helps email clients and servers understand the message's origin, routing, and delivery. Decoding an email header can provide valuable information about the email's journey from sender to recipient.

Here's a breakdown of the main components of an email header:

1. From: The sender's email address.
2. To: The recipient's email address.
3. Subject: The email's subject line.
4. Date: The date and time the email was sent.
5. Message-ID: A unique identifier for the email message.
6. Received: A series of lines indicating the email's path from the sender to the recipient, including the IP addresses and mail servers involved.
7. MIME-Version: The version of the Multipurpose Internet Mail Extensions (MIME) standard used to format the email.
8. Content-Type: The type of content in the email, such as text/plain or text/html.
9. Content-Transfer-Encoding: The encoding scheme used to transfer the email content.

Here's an example of a decoded 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.example.com (mx.example.com [192.0.2.2]) with SMTP id 1234567890;
    Wed, 12 Jan 2022 14:30:00 +0000
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit

Let's break down the Received line:

• from mail.example.com (mail.example.com [192.0.2.1]): The email was received from the mail server mail.example.com at IP address 192.0.2.1.
• by mx.example.com (mx.example.com [192.0.2.2]): The email was relayed to the mail server mx.example.com at IP address 192.0.2.2.
• with SMTP id 1234567890;: The email was transmitted using the Simple Mail Transfer Protocol (SMTP) and has a unique identifier 1234567890.
• Wed, 12 Jan 2022 14:30:00 +0000: The email was received at the specified date and time.

By analyzing the Received lines, you can reconstruct the email's path from the sender to the recipient, including the IP addresses and mail servers involved.

Keep in mind that email headers can be complex and may contain additional information, such as authentication headers, spam filters, or encryption details. If you're interested in decoding a specific email header, feel free to share it with me, and I'll be happy to help you break it down!