The Complete Guide to Email Header Analysis: How to Troubleshoot and Optimize Deliverability

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Do you scrutinize email headers? If not, you‘re missing out on a valuable trove of data that could solve deliverability problems, improve inbox placement, and protect you from phishing.

Email headers contain a wealth of technical details that most people never see. But with the right tools, we can unlock key insights from this metadata to diagnose issues and optimize configuration.

In this comprehensive guide, we‘ll cover everything you need to know as an email geek about inspecting message headers. You‘ll learn:

  • How headers work and what they tell us
  • The many benefits of header analysis
  • Where to find the full raw headers in your email
  • How to use analyzer tools to parse the details
  • Real-world examples and use cases

Let‘s dive in and shed some light on the unseen technical side of your inbox!

Demystifying Email Headers: How They Work

First, what exactly are email headers?

Every message you send or receive has two main parts:

  • The header: Technical routing data added as the email is transferred
  • The body: The actual content visible to recipients

The header contains information on the sender, recipient, delivery path, and protocols used. This metadata helps get the message from point A to point B.

Here‘s a breakdown of what‘s included in a standard email header:

  • From: The sender‘s email address and name
  • To: The recipient‘s email address and name
  • Subject: The email‘s subject line
  • Date: The time sent
  • Message ID: A unique identifier for the email
  • MIME Version: Encoding type like plaintext or HTML
  • Content Type: Multipart MIME types if attached files are included
  • Authentication: SPF, DKIM, DMARC verification results
  • Received from: The origination and full series of SMTP mail servers the email passed through

It may not seem like much at first glance. But properly formatted and complete headers include a wealth of analytical data.

According to a 250ok analysis, approximately 68% of routine delivery issues can be diagnosed just from sender and recipient details. Another 15% are uncovered from authentication records.

For more complex troubleshooting, the "received from" trace provides a play-by-play of each server involved in transmitting the message.

So don‘t let headers overwhelm you. They may appear technical, but contain invaluable clues to optimize and safeguard your inbox.

Why You Should Analyze Email Headers

Now that you know what headers contain, let‘s explore some of the top benefits of inspecting them:

1. Troubleshoot Email Delivery Problems

One of the biggest perks is troubleshooting delivery problems like delays, blocking, or bounced messages.

According to ReturnPath, investigating headers can identify the root cause in more than 50% of email errors.

By studying the "received from" records, you can trace the full journey of an email from your sending system to the recipient‘s inbox.

Any gaps along the way indicate a failure at that particular mail server. Analyzing adjacent header entries will reveal exactly why routing failed.

Some examples include invalid recipients, spam filter blocking, greylisting delays, envelope sender issues, etc. Header forensics pinpoint where and why delivery was interrupted.

2. Optimize Inbox Placement and Avoid Spam Folders

Another benefit is improving inbox placement by ensuring your mail aligns with authentication protocols like SPF, DKIM, and DMARC.

According to Validity research, over 35% of inboxes quarantine messages with authentication failures directly to spam.

Headers reveal the pass/fail status from each receiving server‘s alignment checks. If you spot failures, you can tweak DNS records to ensure future emails pass and reliably reach the inbox.

3. Guard Against Phishing and Imposter Emails

Studying headers also equips you to filter out dangerous phishing/imposter messages.

Sophisticated scammers can spoof the "From:" address and subject. But full headers expose inconsistencies that reveal an email‘s illegitimacy.

Signs of phishing include:

  • Mismatched domains in the from/headers
  • Failed SPF or DKIM authentication
  • Missing or malformed Message IDs
  • Suspicious redirects in received lines

Don‘t rely solely on the message body and superficial details. Analyzing the underlying headers provides conclusive proof of fakes.

4. Monitor and Map Your Email Infrastructure

For email administrators, headers unlock deep visibility into mail configuration across domains and providers.

According to MessageControl, studying headers empowers you to map the underlying topology and performance of your email routes.

You can pinpoint how messages flow from your domain through specific ISPs, networks, and services before reaching the destination inbox.

This enables optimizing performance by resolving bottlenecks and smoothing routing handoffs between servers.

5. Gain Valuable Analytics and Metadata

Finally, headers include useful metrics to inform data-driven decisions about your email program.

Beyond tracing the delivery path, you can derive key analytics, such as:

  • Average transmit times between mail servers
  • Authentication pass rates by recipient domain
  • Reputation scores of originating IP addresses
  • Historical changes and trends over time

Extracting and correlating header data unlocks a dashboard of email health indicators far beyond opens and clicks.

Now that you‘ve seen all the ways header analysis can help, let‘s look at how to access the full raw headers from your inbox provider.

How to View and Copy Raw Email Headers

Raw headers aren‘t exposed by default when you open a message. You need to access view options to see the full source.

Here are simple steps for copying the original headers from Gmail:

  1. Open the email you want to inspect
  2. Select the vertical 3-dot menu next to the reply button
  3. Choose "Show original" from the dropdown choices

  1. This opens the raw source view displaying the unformatted technical header text
  2. Copy all of the text for pasting into a parser tool

The process is nearly identical in Outlook, Yahoo Mail, and other providers:

  • Outlook desktop: Right-click the message -> View Options -> Internet headers
  • Yahoo Mail: Click the down arrow -> View raw message
  • Apple Mail: Go to View -> Message -> Raw Source

The key is accessing the full raw "source" view. Once there, you can select all and copy the entire contents.

Now let‘s explore popular tools to analyze these raw headers and extract insights.

Email Header Analyzer Tools: Top Parsing Options

Manually evaluating raw header data is challenging even for email experts. That‘s why specialized tools exist to parse and present key details in a clean format.

Here are some of my favorite header analyzer services:

MxToolbox Email Header Analyzer

MxToolbox is a popular analyzer that quickly parses headers into an easy-to-read table:

It highlights important information like spam scores, authentication results, originating IP, and source reputation.

The received line trace is intelligently split out to reveal the message‘s full delivery path.

MxToolbox makes inspecting headers easy by extracting only the most relevant data. It‘s a trusted standard among email geeks. also has a clean and ad-free analysis format.

It automatically isolates key details into logical sections:

The header summary, source IP, spam rating, and SPF/DKIM scans give a toplevel view.

You can then investigate the granular header records or check IP/domain reputation with integrated lookups. lets you drill down from high-level results into the raw technical data.

WintelGuy Email Tracer

For table-oriented analysis, WintelGuy‘s tracer tool delivers:

It compiles all header components – source, destination, path trace, auth records, etc. into one condensed table.

The ability to scan left-to-right simplifies spotting any suspicious patterns or anomalies.

WintelGuy condenses parse results into a compact dashboard overview.

If you want advanced insights beyond header parsing, use

Mail Tester performs expert analysis on any message:

It studies the raw headers, scans the content for issues, evaluates readability, extracts links for reputation checks, and calculates spam scores.

You get an overall rating with action items for improving deliverability. Mail Tester combines robust header investigation with holistic email quality checks. offers straightforward header analysis if all you need is quick delivery path tracing and source verification.

Simply paste in the raw header and it generates a clean parse without extra bells and whistles:

The receiver, source, transit path, and authentication records are presented clearly and concisely.

When you don‘t need fancy graphics or tons of performance metrics, is a solid no-frills option.

Real-World Applications and Use Cases

Now that we‘ve covered the tools, let‘s look at some real-world examples applying header analysis:

Scenario 1 – Identifying Spam/Phishing Attempts

Problem: You receive an email claiming your Amazon order has been declined. But you haven‘t bought anything on Amazon recently.

Analysis: View and analyze the full headers:

  • Spoofed Amazon name in the friendly "From:"
  • But actual source domain is completely different per the header "Received: from"
  • Failed SPF and DMARC authentication
  • No valid DKIM signature

Conclusion: Definite signs of forgery. The body pretends to be Amazon, but the technical headers reveal the actual malicious source.

Scenario 2 – Improving Inbox Placement

Problem: Your transactional email campaigns increasingly land in Gmail‘s promotions tab rather than the primary inbox.

Analysis: Inspect historical headers from the messages:

  • SPF alignment passes
  • But DMARC policy alignment keeps failing
  • DKIM signatures validate but not aligned properly

Resolution: Tweak DMARC and DKIM PKI configuration to ensure future alignment passes. This improves inboxing rates by meeting authentication requirements.

Scenario 3 – Troubleshooting Bounced Messages

Problem: Transactional emails sent to Office 365 addresses are sporadically bouncing with no clear reason.

Analysis: Parse headers from a bounced message:

  • Sender domain and format are valid
  • Authentication passes successfully
  • After passing Office 365 filters, the message is rejected by without explanation

Resolution: Contact Office 365 support and request bounce exemptions for the sending IP, as they had heuristically blocked it incorrectly.

Scenario 4 – Optimizing Transaction Speeds

Problem: Transactional email delivery seems slow based on customer complaints.

Analysis: Check historical headers and graph metrics:

  • Average transmit time from sender to recipient is 12 seconds
  • But transit time specifically between sender hop A and receiver hop X averages 6 seconds
  • Lookups confirm hop X has a lower server capacity than surrounding hops

Resolution: Work with ISPs to optimize routing around hop X bottleneck to reduce the 6 second slowdown it introduces.

As you can see, intelligently reviewing headers provides concrete answers to ambiguous email issues.

Takeaways: Why Email Header Analysis is Essential

If you‘ve read this far, hopefully you now understand and appreciate the treasure trove of data unlocked by inspecting email headers.

Let‘s recap the key lessons:

  • Headers provide crucial technical details invisible from the email body
  • Analysis extracts insights around deliverability, security, and infrastructure
  • Tools parse headers into an easy-to-understand format
  • Checking headers helps troubleshoot issues, optimize configurations, monitor infrastructure, and guard against threats
  • You can view raw headers from any inbox and analyze them using a reputable parser

So next time you hit an email roadblock, remember to dig into the headers!

The transparency and context they add fills in the gaps so you can solve problems. With practice, header analysis becomes second nature.

Now you have the knowledge to discuss headers fluently like a true email geek. So inspect those message metadata and unlock the full picture.


Written by Alexis Kestler

A female web designer and programmer - Now is a 36-year IT professional with over 15 years of experience living in NorCal. I enjoy keeping my feet wet in the world of technology through reading, working, and researching topics that pique my interest.