Message Header Analyzer: Decode Headers & Fix Email Issues

Key Takeaways

Message headers contain valuable information that can help diagnose delivery issues and track malicious activities.
Viewing message headers can provide insights into the sender’s email address, IP address, and message transmission path.
Utilizing message header analyzers can streamline the process of troubleshooting email delivery problems and enhance security analysis.
Organizations use message header analysis to ensure compliance with email standards and to monitor the handling of sensitive information.
The PowerDMARC Message Header Analyzer offers in-depth analysis and a user-friendly interface for understanding email authentication headers.
For CISOs and IT managers: Ensure your organization meets Google, Microsoft, and industry compliance mandates by verifying authentication headers on every email.

Email message headers carry critical details about your email’s journey – from sender authentication to delivery routes. By analyzing them, you can find delivery issues, detect spoofing attempts, and ensure compliance with authentication protocols like SPF, DKIM, and DMARC.

For CISOs and IT managers in regulated industries, message header analysis is essential for compliance and rapid incident response.

A message header analyzer, sometimes referred to as an email header analyzer, is an online analysis tool that helps decode and interpret this technical data into human-readable insights.

What is a Message Header?

A message header is a section of an email that contains technical details about how the message was created, transmitted, and delivered. It provides key insights into your email’s journey and authentication status.

Think of a message header as the “passport” for your email, documenting every checkpoint it passes through.

It typically includes:

Sender and recipient addresses
Servers the message passed through (“Received” lines)
Authentication results such as SPF, DKIM, and DMARC
Metadata like timestamps, message IDs, MIME types, and priority flags

Message headers are essential for tracking, troubleshooting, and verifying email authenticity. Beyond basic routing information, headers carry technical metadata used for authentication and security. This includes SPF results, DKIM signatures, and DMARC alignment status, as well as message IDs, MIME types, and priority flags. Each server involved in the delivery process adds its own “Received” line, allowing you to trace the full path an email took to reach its destination.

Why You Should Analyze Message Headers

Analyzing message headers gives you a behind-the-scenes view of how your emails travel from sender to recipient. By understanding the metadata, you can pinpoint issues that affect deliverability, security, and authentication.

Identify delivery problems and delays: Headers show each server your email passed through and timestamps, helping you spot bottlenecks or misconfigurations.
Spot phishing, spoofing, and spam attempts: Suspicious sources, unexpected forwarding, or inconsistent metadata often appear in headers, enabling early detection of malicious emails.
Verify DMARC, SPF, and DKIM compliance: Headers contain authentication results, so you can confirm whether your messages are properly aligned and passing security checks.
Understand email routing and server paths: Reviewing “Received” lines helps you see the exact path your email took, which is useful for troubleshooting and optimizing campaigns.
Meet Google/Microsoft compliance mandates
Instantly identify authentication failures across all domains
Reduce support tickets for MSPs

PowerDMARC delivers instant, actionable insights for security-conscious organizations and MSPs alike.

Analyze Message Headers with PowerDMARC!

Common Challenges Solved by PowerDMARC’s Analyzer

Lack of full visibility into email authentication failures
Complex troubleshooting across multiple domains or clients
Pressure to meet compliance mandates (GDPR, PCI DSS, Google/Microsoft)
Manual investigation of delivery issues

Why PowerDMARC?

Centralized dashboard for all domains and clients
Automated compliance and threat detection
24/7 global support with real technical expertise
Purpose-built for enterprises and MSPs

MSPs: Use PowerDMARC’s analyzer to streamline header troubleshooting across all your client domains from a single dashboard.

Start 15-day trial See PowerDMARC in action. Book a personalized demo

How to View Email Headers in Different Email Clients

To view message headers in various email clients and webmail services, follow these general steps:

1. Google/Gmail

Open the email > Click the three dots (more options) button > Select “Show original.” This will open a new tab or window displaying the full message headers and content.

2. Microsoft Outlook (Web Version)

Open the email > Click the three dots (more actions) button > Choose “View message details.” This will open a pop-up window with the full message headers.

3. Microsoft Outlook (Desktop Version)

Open the email > Double-click the email to open it in a separate window > Click “File” menu (or “Message” tab in some versions) > Select “Properties.” This will display a dialog box with the message properties, including the headers, under the “Internet Headers” section.

4. Apple Mail (macOS)

Open the email > Click “View” > Select “Message” > “All Headers.” This will display the full message headers in a separate section within the email.

5. Thunderbird

Open the email > Click “View” > Select “Message Source.” This will open a new window displaying the full message headers and source code.

Understanding Key Email Header Fields

Message headers are composed of several fields. Below are some key fields explained:

Header Field	Purpose	What Abnormal Values Indicate
From:	Sender’s email address	Mismatched domains may indicate spoofing
To:	Recipient’s email address	Multiple recipients in BCC may indicate spam
Subject:	Subject line of the email	Suspicious keywords or encoding issues
Date:	Message sent timestamp	Future dates or significant time discrepancies
Received:	Path of servers handling the message	Unusual routing or suspicious server locations
Message-ID:	Unique message identifier	Duplicate IDs may indicate message replay attacks

How to Interpret Email Header Fields

Understanding how to read and interpret email header fields is crucial for identifying security threats and delivery issues. Here’s what to look for in each key field:

Authentication-Results Field

This field shows SPF, DKIM, and DMARC validation results. Look for:

spf=pass: Sender is authorized
spf=fail: Unauthorized sender (potential spoofing)
dkim=pass: Message integrity verified
dmarc=pass: Message passes domain policy

Received Lines Analysis

Each “Received” line represents a server hop. Analyze for:

Unusual geographic routing patterns
Excessive delays between hops
Unknown or suspicious server names

Return-Path vs From Address

Compare these fields to detect spoofing:

Return-Path should match the sending domain
Mismatched domains indicate potential impersonation

Common Issues Identified in Email Headers

Email headers can reveal various problems that affect deliverability and security. Here are the most frequent issues and their header signatures:

1. Email Spoofing Indicators

SPF failures: Authentication-Results shows “spf=fail”
Domain mismatches: Return-Path domain differs from From domain
Missing DKIM signatures: No DKIM authentication results

2. Delivery Delays and Routing Issues

Long timestamp gaps: Excessive delays between Received lines
Unusual routing: Messages taking indirect paths through multiple countries
Blacklisted servers: Known spam servers in the delivery path

3. Authentication Failures

DMARC policy violations: “dmarc=fail” with policy enforcement
Alignment issues: SPF/DKIM pass but DMARC fails due to alignment
Missing authentication: No SPF, DKIM, or DMARC checks performed

Actionable Steps When You Find Suspicious Headers

Document the suspicious indicators for security teams
Block the sender’s IP or domain if confirmed malicious
Update SPF/DKIM records if authentication failures are legitimate
Report phishing attempts to relevant authorities
Review and strengthen DMARC policies

How to Analyze Message Headers Using a Message Header Analyzer

Here’s how PowerDMARC solves the most common header-related challenges for security teams.

Simply paste or upload your email headers into PowerDMARC’s Message Header Analyzer.

PowerDMARC’s analyzer doesn’t just decode headers. It gives you actionable insights to stop threats and ensure compliance in seconds.

The tool instantly provides a detailed breakdown, including:

SPF, DKIM, and DMARC authentication results
Alignment and policy status
Return Path and From address details
Additional checks such as MTA-STS, TLS-RPT, and BIMI compliance

Here’s how to use it:

Step 1: Send a Test Mail or Upload Headers

On the tool page, send an email to the provided address or upload the email header to get your results. It will be listed in the table once we receive it.

Alternatively, upload your headers by copying and pasting them into the text box.

Step 2: Analyze Results

Click on the “view” icon to view your detailed report. Here, you should be able to see all the information about your messages’ authentication headers, alignment status, published DMARC policy mode, DKIM, SPF, MTA-STS, and BIMI compliance, Return Path, and From address, along with other relevant information.

4. View Raw and Parsed Message Header Formats

If you wish to view your message headers in their raw, original format, you can click on the “raw” tab and view the subsequent results. You also get to analyze message headers in a parsed, human-readable format by clicking on the “Human” tab as shown below:

Email Header Analyzer Use Cases

Message header analyzers serve various practical purposes across different organizational roles and scenarios:

Security Investigations

Phishing Detection: Analyze suspicious emails to identify spoofing attempts and malicious sources
Incident Response: Trace email origins during security breaches to understand attack vectors
Threat Intelligence: Gather information about malicious infrastructure and attack patterns

Compliance and Legal

Regulatory Compliance: Verify email authentication meets GDPR, PCI DSS, and industry requirements
Legal Discovery: Authenticate email evidence for litigation and forensic investigations
Audit Trails: Document email security posture for compliance reporting

IT Operations

Deliverability Troubleshooting: Diagnose why legitimate emails are being blocked or marked as spam
Configuration Validation: Verify SPF, DKIM, and DMARC implementations are working correctly
Performance Monitoring: Identify email routing issues and delivery delays

Benefits of Using a Message Header Analyzer

A message header analyzer helps you uncover critical insights hidden in your email headers. It allows for:

Quick troubleshooting of email delivery issues
Detection of spoofing or phishing attempts
Verification of DMARC, SPF, and DKIM authentication compliance
Better visibility into email routing paths and source servers

Analysis Method	Time Required	Accuracy	Expertise Required
Manual Analysis	30–60 minutes	Variable	High
Automated Analyzer	2–5 minutes	Consistent	Low

For IT managers: Quickly diagnose delivery issues.
For MSPs: Troubleshoot client problems in one dashboard.

Best Practices for Using a Message Header Analyzer

Review headers frequently: Regularly review headers after making DNS or policy changes to avoid configuration issues or unwanted authentication failures.
Analyze suspicious emails: This helps promptly detect potential fraud, unknown sources, and impersonation attempts.
Choose wisely: Skip the hassle, use analyzers that present data in a clear, human-readable format, like PowerDMARC.

CISOs: Review headers after every policy change for compliance.

MSPs: Use batch analysis for multiple client domains.

PowerDMARC delivers instant, actionable insights for security-conscious organizations and MSPs alike.

Frequently Asked Questions

What information can I find in an email header?

Email headers contain sender and recipient information, server routing paths, timestamps, authentication results (SPF, DKIM, DMARC), message IDs, and technical metadata. This information helps trace email origins, verify authenticity, and troubleshoot delivery issues.

How do I know if an email is spoofed from the header?

Look for SPF failures (spf=fail), mismatched Return-Path and From domains, missing DKIM signatures, DMARC policy violations, and unusual routing patterns. Suspicious timestamps, unknown servers in the delivery path, and inconsistent sender information are also red flags.

Can I use a header analyzer for compliance or legal investigations?

Yes, header analyzers are valuable for compliance verification (GDPR, PCI DSS), legal discovery, and forensic investigations. They provide documented evidence of email authentication status, routing paths, and security posture that can be used in audits and legal proceedings.

Final Words

Analyzing message headers is a simple yet powerful way to strengthen your email security posture. By using a reliable header analyzer and following best practices, you can identify delivery issues, spot threats early, and ensure your authentication protocols work as intended.

Get started with the best in the game, sign up for aStart 15-day trial of PowerDMARC to get access to our message header analyzer and many more analysis tools today!

About
Latest Posts

Ahona Rudra

Domain & Email Security Expert at PowerDMARC

Ahona is the Marketing Manager at PowerDMARC, with 5+ years of experience in writing about cybersecurity topics, specializing in domain and email security. Ahona holds a post-graduation degree in Journalism and Communications, solidifying her career in the security sector since 2019.

What is a Message Header Analyzer? (And How to Use It)