Have you ever had someone claim that they didn’t get your email—that it “ended up stuck in the internet somewhere?” Or more realistically, have you ever had deliverability problems in an email marketing campaign that you just couldn’t figure out? These are cases where you may need to use an email header analyzer.

You can diagnose and troubleshoot a lot of email delivery problems (and more details about your email campaign) by analyzing a few lines of text at the beginning of the email.

So what exactly is this “email header,” and how can you perform an email header analysis?

What Are Email Headers?

You can think of an email in terms of its basic anatomy. There’s the envelope, the body of the message, and its header. The body of the message is something you’re already familiar with—it’s the content you write. The envelope is something you generally don’t need to think about; it’s part of an internal process that’s used to route the email.

An email header is something different. When emails are sent, the body of the message is part of the transmission (obviously).

But preceding that core content are header lines that include information like the sender, the recipient, the subject line, and the date; these bits of information are parsed by your email client, and some are made visible to you so you have a better understanding of the message’s context.

The best way to conceptualize an email header is to see an example of a full email header in action. Let’s take a look at this example from What Is My IP Address:

Return-Path: <example_from@dc.edu>

X-SpamCatcher-Score: 1 [X]

Received: from [] (HELO dc.edu)

    by fe3.dc.edu (CommuniGate Pro SMTP 4.1.8)

    with ESMTP-TLS id 61258719 for example_to@mail.dc.edu; Mon, 23 Aug 2004 11:40:10 -0400

Message-ID: <4129F3CA.2020509@dc.edu>

Date: Mon, 23 Aug 2005 11:40:36 -0400

From: Taylor Evans <example_from@dc.edu>

User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.0.1) Gecko/20020823 Netscape/7.0

X-Accept-Language: en-us, en

MIME-Version: 1.0

To: Jon Smith <example_to@mail.dc.edu>

Subject: Business Development Meeting

Content-Type: text/plain; charset=us-ascii; format=flowed

Content-Transfer-Encoding: 7bit

Why Would You Want to Analyze Email Headers?

So why would you want to analyze email headers?

For starters, email headers contain basic information about the nature of an email, including things like:

  • From. The From field represents the sender.
  • To. The To field represents the recipient.
  • Date. The Date and Time fields tell you when an email was sent.
  • Subject. The Subject line… well, you know what a subject line is.

Of course, you probably have access to these data already.

Even better, headers contain routing information relevant to the passage of the message from one computer to another. Mail transfer agents (MTAs) are used to manage this process; each time an email is sent or forwarded by an MTA, it’s stamped with date, time, and recipient information.

Again, thanks to What Is My IP Address, here’s a great example of how it looks:

Received: from tom.bath.dc.uk ([] ident=yalrla9a1j69szla2ydr)

        by steve.wrath.dc.uk with esmtp (Exim 3.36 #2)id 19OjC3-00064B-00

        for example_to@imaps.bath.dc.uk; Sat, 07 Jun 2005 20:17:35 +0100

Received: from write.example.com ([])

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        by tom.wrath.dc.uk with esmtp id 19OjBy-0001lb-3V

        for example_to@bath.ac.uk; Sat, 07 Jun 2005 20:17:30 +0100

Received: from master.example.com (lists.example.com [])

        by write.example.com (Postfix) with QMQP

        id F11418F2C1; Sat, 7 Jun 2005 12:34:34 -0600 (MDT)

Other factors you may see include things like:

  • Received. The Received field shows that an email has reached its intended recipient’s mailbox.
  • Domain key signatures. Domain key signatures and domain key identified mail (DKIM) signatures function as part of an email signature ID system.
  • MIME version. MIME is a traditional internet standard that improves how an email functions; this states which version the email is using.
  • Content type. Content type tells you whether the email is plain text or HTML.
  • X-Spam status/level. X-Spam factors, including status and level, can tell you the subjective spam score of an email and its threat level.

At this point, you’re probably grateful that your email client regularly hides most of this information. But if you’re interested in more details about the emails you’re sending or receiving, this can be a useful tool for analyzing things like:

  • Mail routing. How many jumps did this email make before it reached its destination? Which MTAs were being used?
  • Delay identification and analysis. Were there any significant delays between your initial send and its final delivery? If so, what were the root causes?
  • Anti-spam analysis. Is your email getting flagged as spam? If so, where is it getting flagged as spam, and why?

If you want to maximize your email marketing campaign results, this information could be crucial.

Now, let’s dig into the actual process of email header analysis.

How to Analyze Email Headers in Gmail

Before you can analyze an email header, you first need to obtain it. Here’s how to do that in Gmail:

  1. Open Gmail.
  2. Find the message you want to analyze.
  3. Click the three vertical dots in the upper-right of the message.
  4. Click “Show Original.”

Gmail email header analyzer

Here, you’ll see a brief breakdown of the information found in the header. If you scroll down, you can also see the full text of the email header, which will end just before the body content of the message.

From there, you can copy the email header into an email header analysis tool to learn more details.

How to Analyze Email Headers in Outlook

Here’s how to obtain your email header in Outlook:

  1. Open Microsoft Outlook.
  2. Click on the message you want to analyze.
  3. Click on the dropdown arrow in the upper-right of the message.
  4. Click “View message details.”

Outlook email header analysis

Here, you’ll see the full text of the email header.

From there, you can copy the email header into an email header analysis tool to learn more details.

Email Header Analyzer Tools

Once you have a copy of the email header, you can analyze it using one of the following email header analysis tools.

Almost all of these tools are free, and function in the same way, so I won’t go into detail describing the minor differences. With all of them, you’ll copy and paste your email header, click a button, and review the information after it is parsed.

1. G Suite Toolbox Messageheader.

If you’re already using Gmail, you might as well try G Suite’s Messageheader tool.

2. Mx Toolbox.

Mx Toolbox has a great standalone email header analyzer, as well as detailed information on email headers for the uninitiated.

3. What Is My IP?

We’ve already credited them for their helpful email examples, but What Is My IP also has a convenient email header analysis tool.

4. Mailheader.org.

There’s also Mailheader.org, where you can review mail header samples in addition to the header you’ve selected.

5. Gaijin.

In case you needed more options, you could also try Gaijin.

If the above email header analyzer tools return an error message, or if there’s a bit of information you were unable to find in their analysis, consider manually reviewing the email headers yourself.

It may seem intimidating, especially if you have no experience with code or XML files, but chances are, you can parse the text to find the information you seek—or at least identify a missing space where the information should be.

So, which is the best email header analyzer? Well, they all function pretty much the same, so just start with Google’s Messageheader tool and move down the list if that doesn’t give you what you need! And be sure to see our list of the best bulk email services for a list of tools we recommend using for your needs.

Are you looking for more tools you can use to analyze emails? Consider a tool like EmailAnalytics. EmailAnalytics functions like Google Analytics, but for Gmail; once integrated, you’ll be able to view details of your account like how many emails you send and receive, your average email response time, and more.

You can also use EmailAnalytics with any of your employees’ accounts, so you can track their email activity. Sign up for a free trial today to see how it works!