A few months ago, I launched a free Chrome extension called Email Detective. It now has almost 600 users!
The idea is simple: open any newsletter in Gmail or Outlook and instantly see which email marketing platform sent it.
Whether it's Mailchimp, Klaviyo, HubSpot, Beehiiv, or one of the 140+ providers the extension recognizes, Email Detective reveals the technology behind the email with a single click.
It also reveals the technical details most people never look at – but absolutely should – including:
- SPF
- DKIM
- DMARC
- BIMI & VMC
More recently, I added support for detecting email template builders such as BeeFree, Stripo, and Topol.
Sometimes it reveals interesting things: like Klaviyo using HubSpot for their own email marketing 😄
What surprised me most wasn't the technology – it was how people started using it.
After collecting feedback from users, I've discovered several use cases I never anticipated. Here are six of the most useful (and creative) ways people are putting Email Detective to work.
1. Spy on Your Competitors' Email Stack
Your competitor's latest newsletter lands in your inbox.
One click later, you know exactly what technology they're using to send it.
This is useful for a couple of reasons.
First, you can compare their email stack to yours. Are they using a similar platform? Or are they paying significantly more for fewer features because they're still stuck on an outdated setup?
Second, if their emails consistently look better than yours, their tools may be part of the reason.
Email Detective now identifies popular email template builders such as BeeFree, Stripo, and Topol. It can also detect whether an email uses AMP for Email, giving you even more insight into what's happening behind the scenes.
Sometimes the fastest way to improve your email marketing is to learn from people who are already doing it well.
2. Audit Your Deliverability in 10 Seconds
Most deliverability audits take time.
This one doesn't.
Simply send yourself a campaign from your email service provider, open it in Gmail/Outlook, and launch Email Detective.
You'll instantly see whether SPF, DKIM, DMARC, and BIMI are properly configured.
If something is missing, misconfigured, or failing authentication checks, you'll know immediately—before your subscribers start experiencing problems.
It will even flag slow delivery for you, as illustrated in the screenshot above. Very slow delivery can be a first warning sign for a greylisting or other reputational issues.
3. Discover What Platform Your Favorite Newsletters Use
Ever wondered what powers newsletters like Morning Brew, The Hustle, or that newsletter that looks like Substack but probably isn't?
Email Detective tells you instantly.
Open any newsletter and see exactly which platform is sending it.
For creators, marketers, and business owners researching email marketing software, this can be incredibly useful for building a shortlist of platforms worth considering.
4. Spot Suspicious Emails Before You Click
Imagine receiving an urgent password reset email claiming to be from PayPal.
Before clicking anything, open Email Detective.
If the message was sent through an unexpected provider and has broken authentication signals or missing DMARC records, that's a warning sign worth paying attention to.
To be clear, Email Detective is not a replacement for dedicated phishing detection tools.
But it can provide a quick sanity check.
When a major brand supposedly sends you an important message, yet the authentication setup looks messy, it's often worth investigating further before taking action.
5. Find Your Next Customer (Consultants and Agencies, This One's for You)
One of the most interesting use cases came from consultants and agencies.
Email Detective includes a free bulk scanner that can analyze multiple emails at once instead of requiring you to inspect them individually.
For deliverability consultants, this creates a surprisingly effective prospecting tool.
You can identify companies actively sending email while suffering from issues such as:
- Missing SPF records
- Broken authentication
- Missing DMARC policies
That gives you a much stronger conversation starter than a generic cold outreach email.
The same idea applies to email service providers and migration consultants.
If you spot companies sending large volumes through expensive legacy platforms, you may have an opportunity to help them reduce costs while improving their setup.
6. Have Some Fun With It
Not every use case has to be serious.
One of my favorite discoveries came while testing the extension.
Without Email Detective, I never would have known that Klaviyo uses HubSpot for some of its own email marketing.
Even more amusing: Beehiiv using Customer.io.
There are probably perfectly reasonable explanations for both.
But it's still funny when email software companies use competing email software companies.
That's the kind of industry trivia you never uncover unless you start looking under the hood.
Try Email Detective
Email Detective is completely free and takes less than a minute to install.
If you're curious about the technology behind the emails landing in your inbox every day, give it a try.
Whether you're researching competitors, troubleshooting deliverability, evaluating email platforms, or just satisfying your curiosity, you'll probably learn something interesting.
And if you discover a clever use case—or an email service provider I've missed—I'd love to hear about it.
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This article has been written and researched following our EmailTooltester methodology.
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