How to Verify Email Header Integrity

Email headers contain important metadata that provides critical information about an email’s authenticity, integrity, and security. Verifying email headers is an essential process to ensure emails are legitimate and have not been compromised. This article will provide a detailed guide on techniques and best practices for verifying email header integrity.

What are Email Headers

An email header refers to metadata located at the top of an email message, before the body content. It contains key details such as:

  • Sender’s email address: The originating email address of the sender.
  • Recipient’s email address: The intended recipient’s email.
  • Subject line: A brief summary of the email topic.
  • Date/time sent: When the email was originally sent.
  • Message ID: A unique ID assigned to track the email.
  • Received headers: Logs of each server the email passed through.

Email headers provide a digital envelope that accompanies every email as it travels from sender to recipient. Analyzing headers reveals critical information about an email’s journey and verifies its authenticity.

Why Verify Email Headers

There are several key reasons to verify email headers:

  • Detect spoofing/phishing: Headers can reveal signs of email spoofing, such as inconsistencies in sender addresses. This allows early detection of phishing attempts.
  • Check authenticity: Details in headers like message IDs can confirm an email came from expected sender.
  • Understand routing: Received headers trace an email’s journey, highlighting any suspicious servers.
  • Troubleshoot issues: Headers provide diagnostics to pinpoint email delivery problems.
  • Forensic analysis: In case of security incidents, headers provide pivital clues for investigations.

Overall, verifying headers is crucial for individuals and organizations to make informed decisions about the legitimacy of an email before opening attachments or links.

How to Read Email Headers

Email headers contain technical details that may appear cryptic at first glance. Here is a step-by-step guide to reading headers:

1. Locate the Full Email Header

  • In webmail (e.g. Gmail), click “Show Original” or “View Source” to access full headers.
  • In email clients (e.g. Outlook), check options for “Internet Headers”, “Raw Source” etc.

2. Identify Key Header Components

Key details include:

  • Received: Traces path from originating server to your inbox.
  • Return-Path: The envelope sender where bounces/errors go.
  • From: The sender email address visible to recipient.
  • To: Email address of intended recipient.
  • Subject: Topic summary visible to recipient.
  • Message-ID: Unique ID to track the email.

3. Review Authentication Mechanisms

Key protocols that verify sender validity:

  • SPF checks approved sending servers.
  • DKIM confirms email has not been tampered.
  • DMARC aligns SPF/DKIM checks with visible sender.

4. Check for Red Flags

Watch for:

  • Unexpected source IP addresses
  • Messages coming from suspicious servers
  • Failed SPF, DKIM, or DMARC tests
  • Changes in email content noted in headers

5. Trace Email Journey

The “Received” headers logged at each server reveal the network path of an email. Review these to check for suspicious patterns.

Best Practices for Verification

To thoroughly verify email header integrity, follow these best practices:

Compare header details – Cross-check information in From, Sender, Reply-To fields for consistency.

Review authentication status – Check SPF, DKIM & DMARC results to confirm validity.

Examine all received headers – Trace entire journey from originating server into inbox.

Understand email protocols – Learn to interpret SPF, DKIM & DMARC specifications correctly.

Check for red flags – Watch for unexpected changes in content, failed tests.

Use email header analyzer tools – Services like MxToolbox parse headers and highlight issues.

Conduct periodic sampling – Spot check legitimacy of random emails received.

Following structured verification steps and reviews will help individuals and organization flag suspicious emails early.

Tools for Email Header Analysis

Specialized tools can parse raw email headers and extract insights to assist in the verification process:


MxToolbox’s Email Header Analyzer checks headers against standards like SPF, DKIM, and DMARC to evaluate authentication status. The results clearly highlight any issues for easy interpretation. simplifies email headers to make them human-readable. The tool breaks down key header components like sender, recipient, subject line and message ID into an easy-to-understand format.

Message Header Analyzer

For Gmail users, the Message Header Analyzer in Google’s Admin Toolbox parses headers and checks authentication to reveal useful delivery diagnostics.

Email On Acid

Services like Email On Acid goes beyond header analysis to preview and test emails across different email clients and devices to surface rendering issues.


For enterprise-grade protection, Valimail automates implementation of email authentication protocols like DMARC and provides detailed analytics on email traffic and threats.

Key Takeaways

Verifying email header integrity is essential for security:

  • Headers provide critical details about email authenticity and journey.
  • Review sender details, authentication mechanisms and route to check legitimacy.
  • Watch for failed authentication tests, changes in content.
  • Use email header analyzer tools for efficient verification.
  • Implementing checks protects organizations from phishing threats.

Following email header best practices improves visibility into threats and ensures only emails from trusted sources make it to the inbox.