Understanding Email Headers

What Are Email Headers?

Email headers are the hidden metadata that travel with every email message. While the body of an email contains the actual content you read—like the message, images, or attachments—the headers contain technical details about how the email was sent, where it came from, and how it was routed. They act like the envelope and postmarks of digital mail, recording each step along the way from sender to recipient.

Headers include fields such as the sender and recipient email addresses, the subject line, timestamps, and a trail of server “Received” entries showing the email’s journey. They also carry authentication information (like SPF, DKIM, and DMARC results) that help mail servers determine if a message is legitimate or potentially spoofed. While most email clients only display a simplified view (From, To, Subject, Date), viewing the full headers gives you powerful insight into an email’s trustworthiness and technical makeup.

Why email headers matter

Email headers are like the "shipping label" of an email - they contain hidden information that helps you understand where an email came from and whether you can trust it. Here's why they're important:

Tracing an email's origin and path

Headers show the complete journey an email took to reach you, like tracking a package. This helps you:

• See if an email claiming to be from your bank actually came from their servers
• Identify suspicious detours through unknown servers
• Understand delays in email delivery

Verifying email authenticity

Modern email uses security protocols (SPF, DKIM, DMARC) that leave verification clues in the headers. These help you:

• Confirm the sender is who they claim to be
• Spot forged "From" addresses used in phishing scams
• Check if an email passed authentication checks

Diagnosing delivery problems

When emails go missing or arrive late, headers provide clues like:

• Which mail server might be causing delays
• If the email was rejected by spam filters
• Whether forwarding services are causing issues

Identifying spam or phishing attempts

Headers reveal warning signs that aren't visible in the message itself:

• Mismatches between the "From" address and actual sender
• Suspicious server locations
• Missing or failed authentication checks
• Known spammer IP addresses

By learning to check headers, you gain an extra layer of protection against scams and can better understand email delivery issues.

Key Header Fields and Their Importance

Real-World Examples

1. The Fake Bank Email

   • Claimed to be from "security@yourbank.com"
   • Headers showed it actually came from a server in another country
   • Authentication-Results showed DKIM failed

2. The Urgent Invoice Scam

   • From address matched your CEO's name
   • Return-Path revealed a completely different domain
   • Received headers showed it was forwarded through a free email service

3. The Missing Package Notification

   • Looked like a legitimate shipping company email
   • X-Spam-Score was extremely high (15/15)
   • No SPF or DKIM authentication present

By checking these header details, you can spot red flags that aren't visible in the email's content alone.

How email headers differ from email content

Think of an email like a letter in an envelope:

The Email Content (Body)

• What you see when you open the email
• Contains the actual message text
• Includes any attachments
• Similar to the letter inside an envelope

The Email Headers

• Hidden technical details (normally not shown)
• Like the postmarks and stamps on an envelope
• Contains important information about:
  • Who really sent it (not just the "From" name)
  • The path it took to reach you
  • Security checks it passed (or failed)
  • When each server handled the message

Why This Matters

Understanding this difference helps you:

• Spot fake emails (where headers don't match content)
• Diagnose delivery problems
• Verify important messages are genuine
• Understand why some emails get marked as spam

Example: A phishing email might say it's from your bank in the content, but the headers reveal it actually came from a completely different server.

What Email Headers Look Like

Headers appear as technical text showing:

• The path the email took (like a travel log)
• Security verification results
• Server timestamps
• Original sender information

Why Check Headers?

Viewing headers helps you:

• Verify if an email is genuine
• Understand why an email was marked as spam
• Trace delivery problems
• Spot phishing attempts

How to Find Email Headers

Email headers are hidden behind the scenes, but they contain valuable information about an email's journey and authenticity. Here's how to access them in different email programs.

Step-by-Step Guides

📧 Gmail (Web)

1. Open the suspicious email
2. Click the three dots (⋮) in top-right
3. Select "Show original"
4. A new tab opens with all header details

💡 Tip: The colored authentication results at the top quickly show if the email passed security checks.

🖥️ Outlook Desktop (Windows)

1. Double-click to open the email
2. Go to File > Properties
3. Scroll to Internet headers section

📱 Apple Mail (iOS)

Since iOS Mail doesn't show headers directly:

1. Forward the email to yourself on a computer
2. Check headers using the desktop instructions

Other Email Clients

The process is similar across most services:

1. Look for options like:
   • "View original"
   • "Show message source"
   • "View headers"
2. These are typically under the More (⋯) or Settings menu

Using Our Analyzer

After finding the headers:

1. Copy all the header text
2. Paste into FreeEmailAnalyzer
3. Get an easy-to-read breakdown of what it all means

Remember: You don't need to understand all the technical details - our tool translates them into simple insights about the email's authenticity and history.