Name: Email Detective for Gmail: Identify ESPs & Check Authentication
Rating: 5 (12 reviews)
Author: Tooltester

Jun 10, 2026

description

Ever wonder which email marketing tool a company uses? Email Detective tells you instantly.

Open any email in Gmail and see a "Sent via Mailchimp" (or Brevo, HubSpot, Klaviyo, etc.) badge right on the subject line. Click it for details: vendor website, authentication status (SPF, DKIM, DMARC), and whether a shared or dedicated IP address was used.

----
Not using Gmail? We've just released an Outlook version: https://chromewebstore.google.com/detail/email-detective-for-outlo/lfhppcapafocegboaeaejkdamebobafo
----

WHAT IT DETECTS:

-140+ email service providers across marketing platforms, newsletter tools, CRM systems, and transactional email services
-Detects Mailchimp, Brevo, HubSpot, Klaviyo, Salesforce MC and many more
-Infrastructure providers like SendGrid and Amazon SES, with smart detection that shows the actual marketing platform when possible
-HTML builders like Stripo and BeeFree

FEATURES:
-Instant ESP (email service provider) detection when you open any email
-Clickable badge with ESP details popup
-Email authentication checker (SPF/DKIM/DMARC) + BIMI and VMC
-Shows whether it's a shared or dedicated IP (where it can be detected)
-New: bulk scanner. Scan 50 emails at once
-Works in inbox list view for previously opened emails
-100% private: all data stays in your browser

*How to audit your own deliverability in seconds*:
-Send yourself a campaign from your own email marketing service.
-Open it in Gmail and click the "Sent via" label.
-You'll see SPF, DKIM, DMARC and BIMI status laid out cleanly. If something is missing or failing, the label will show a warning triangle.

PERFECT FOR:
-Email marketers researching competitors
-Agencies evaluating client tech stacks
-Deliverability specialists checking authentication
-Anyone curious about the tools behind the emails they receive

Built by EmailTooltester.com, the independent email tool review platform with 15+ years of testing experience.

Free. No account required. No personal data collected.

Changelog:

v1.8.66
-Further detection improvements
-Beefree SDK vs RGE Studio builder detection + the Postcards builder added
-Other minor fixes

v1.8.64
-Detection improvements

v1.8.62
-Minor housekeeping

v1.8.61
-Fixed false detection on personal Gmail emails, fixed DMARC missing-record warning icon

v1.8.58
-Friendlier install — the extension no longer asks for Gmail access at install time. You'll see a clear "Activate on Gmail" prompt the first time you open the popup. (Existing users: no action needed — your setup carries over automatically.)
-Behind the scenes: smoother handling of permission changes, better tab updates after an upgrade.

v1.8.57
-Minor reliability and detection polish

v1.8.54
-Enables faster detection pattern updates

v1.8.53
-Detects dynamic-content vendors (Movable Ink, LiveClicker, Kickdynamic, NiftyImages, Powerinbox) — countdown timers, real-time polls, weather-aware imagery
-Prepares the detective to detect TLS version used to deliver each email
-Prepares the detective to detect schema.org actions Gmail renders as inline buttons (RSVP, Track Order, Confirm, etc.)
-Auth cache now invalidates automatically on extension updates
-Speed improvements and other bugfixes

v1.8.44
-Postcards email builder now detectable + a minor bug fix

v1.8.40
-Detects the underlying SMTP engine — PowerMTA, KumoMTA, Momentum, Halon, GreenArrow, plus self-hosted Postfix/Sendmail/Exim. Shows up as "Powered by [engine]" in the popup.
-Tooltips, we added even more tooltips

v1.8.36
-Delivery time on every email. Parses the Received: chain to show how long the email took from sender to Gmail. Color-flagged: amber at 1+ min, red at 5+ min — quick visual cue when a sender is being throttled or greylisted.

v1.8.27
-Shows DMARC alignment, not just pass/fail
-Plain-English tooltips on every authentication row — SPF, DKIM, DMARC, Unsubscribe, BIMI, VMC — explaining what each one actually means and what the current status implies
-Pattern hardening: fixed substring-trap false positives in ActiveCampaign markers and 8 generic-English-word brand domains

v1.8.11
Detects Gmail's "suspicious message" warnings. Fixes a Substack-detected-as-Mailgun bug.

v1.8.7
-Minor housekeeping update with improved listing title for clearer discoverability.

v1.8.6
-Adds Epsilon, CleverTap, and EcoSend detection. Renames eSputnik to Yespo. Detects Unlayer email builder.

v1.8.2
-Fixes: improved Amazon SES detection.
-Performance improvements (faster loading)

v1.8.0
- New: report incorrect detections from the popup ("Wrong detection? Tell us")
- Cordial, Smaily added
- Better favicon handling for vendors whose apex domain has no /favicon.ico

v1.7.30
-Added smarter ESP attribution by capturing sending subdomain info for SPF analysis

v1.7.27
-Various bug fixes

v1.7.25
-New "Broken authentication" chip when no ESP detected but DMARC/SPF+DKIM definitively fail
-Fixed false ESP attribution from quoted reply chains (multi-line References leak)

v1.7.18
-More ESPs added (Userlist, HubSpot Starter)
-Fewer false positives on forwarded emails
-Accuracy fixes for Marketo/Braze/Tabular/Mailtrap.

v1.7.10
-New ESPs added: Bluecore, OptiPub, Sarbacane and User.com.
-Bug fixes and security improvements

v1.7.9
-HTML builders like BeeFree, Tabular and Stripo now also get detected
-Fewer false positives, especially in replies and forwards
-Favicons in the popup, cleaner layout
-Stats no longer inflated by re-opening the same emails

v1.7.8
New Settings tab with sign-out, cache refresh, and clearer privacy controls.

v1.7.7
-Authentication warning indicator on emails with broken SPF/DKIM/DMARC. Shows a ⚠️ now in the label next to the subject line.
-Reliability fixes for badge display in Gmail's list view.

v1.7.6
-Better detection (120+ ESPs more reliable)
-Smarter inbox tracking — same email isn't re-counted if you reopen it.
-Detection of more technologies (e.g. AMP)

v1.7.5
-More ESPs added (Kajomi, Optimizely Campaign)
-Various detection accuracy improvements

v1.7
-Bulk scan "Next page" works correctly in folders with 1,000+ emails (e.g. Trash)
-Auth detection now scopes to the displayed sender on threads with forwarded messages
-"Unsubscribe" badge label clearer
-Various detection accuracy improvements

v1.6.10
-New: One-click unsubscribe (RFC 8058) status shown for bulk emails. See if a sender meets Google/Yahoo bulk sender requirements
-Bulk scan "Next page" works across more Gmail layouts

v1.6.8
-Bulk scan "Next page" works across more Gmail layouts
-"Unlock" buttons now respond instantly instead of feeling unresponsive
-AWS SES IPs no longer flagged as shared/dedicated since PTR can't distinguish

v1.6.5
Stability improved

v1.6.4
-New: BIMI/VMC detection for registered users (also reflected in stats). Improved Shared vs Dedicated server detection.

v1.6.3
-Improved DMARC statuses in the scanning window
-Smaller detection improvements and new ESPs added

v1.6.2
-Fix for a bug when the preview pane is enabled in Gmail

v1.6.1
-Smaller bug fixes
-Detection improved, more ESPs added

v1.6
-Important new feature: bulk scanner (beta). Try it out and let us know how you like it!

v1.5.1
-Fixing an issue with permissions (extension asked for permissions it doesn't need)

v1.5.0
-Multiple new ESPs added
-Fixes for forwarded emails and DMARC reports.

v1.3.1
-Fixes false positives and adds a new ESP.

v1.3.0
-New: now shows whether a sender is using a shared or dedicated IP address. This helps you understand the sending setup behind any email at a glance.
-Perform a deeper IP reputation lookup by opening Talos (popup includes a direct link now)
-Added more ESPs (Pipedrive Campaigns and Connectif)
-Improved pattern matching for ActiveCampaign, Brevo, and CleverReach

v1.2.3
-New ESPs: Added Seguno and Lettermint
-Fixed: certain Braze customers were detected as SparkPost.
-Fixed: False positive Iterable detection
-About panel in the popup added

v1.2.2
- Fixed false positives for 3 ESPs
- Added/Improved detection for Iterable and Acoustic

v1.2.1:
Added Magnews and Inboxroad ESPs
Improved detection for MailerLite, GetResponse, and Ghost Pro
Reduced false positives in body scanning

v1.2.0
New: ESP Collection tracker in the popup. See how many of the 100+ providers you've spotted so far
Reduced false positives: body scanner now only uses tracking domains, ignoring editorial links to ESP websites
Fixed Substack emails incorrectly showing as Mailgun
Added new ESPs: Maileroo, Mailtrap, PHPMailer, Strato
Infrastructure ESPs no longer override app-level detections

Ever wonder which email marketing tool a company uses? Email Detective tells you instantly.

Open any email in Gmail and see a "Sent via Mailchimp" (or Brevo, HubSpot, Klaviyo, etc.) badge right on the subject line. Click it for details: vendor website, authentication status (SPF, DKIM, DMARC), and whether a shared or dedicated IP address was used.

----
Not using Gmail? We've just released an Outlook version: https://chromewebstore.google.com/detail/email-detective-for-outlo/lfhppcapafocegboaeaejkdamebobafo
----

WHAT IT DETECTS:

-140+ email service providers across marketing platforms, newsletter tools, CRM systems, and transactional email services
-Detects Mailchimp, Brevo, HubSpot, Klaviyo, Salesforce MC and many more
-Infrastructure providers like SendGrid and Amazon SES, with smart detection that shows the actual marketing platform when possible
-HTML builders like Stripo and BeeFree

FEATURES:
-Instant ESP (email service provider) detection when you open any email
-Clickable badge with ESP details popup
-Email authentication checker (SPF/DKIM/DMARC) + BIMI and VMC
-Shows whether it's a shared or dedicated IP (where it can be detected)
-New: bulk scanner. Scan 50 emails at once
-Works in inbox list view for previously opened emails
-100% private: all data stays in your browser

*How to audit your own deliverability in seconds*:
-Send yourself a campaign from your own email marketing service.
-Open it in Gmail and click the "Sent via" label.
-You'll see SPF, DKIM, DMARC and BIMI status laid out cleanly. If something is missing or failing, the label will show a warning triangle.

PERFECT FOR:
-Email marketers researching competitors
-Agencies evaluating client tech stacks
-Deliverability specialists checking authentication
-Anyone curious about the tools behind the emails they receive

Built by EmailTooltester.com, the independent email tool review platform with 15+ years of testing experience.

Free. No account required. No personal data collected.

Changelog:

v1.9.0
-Sender tech, one click away. The email card now has a "More details" expand showing the sending setup: the MTA powering it, Return-Path, CSA certification (if existing), TLS, and the send date.
-Sharper detection. More cleanup of plain domain names that could cause false matches.

v1.8.76
-Sharper detection. We stopped matching plain homepage domains, so senders show the right email provider and fewer false matches slip through.
-Cleaner replies. Replying to a newsletter no longer tags your own reply with that newsletter's email provider.
-Sign up from Settings added.

v1.8.75
-Fixed false warnings on reply threads.
-More accurate detection, fewer wrong matches.

v1.8.73
-More accurate ESP detection: removed a batch of overly broad patterns that could tag the wrong provider.
-Better authentication reads: fixed a case where a "From" address split across two lines made SPF/DKIM/DMARC show as failed when it actually passed.
-Pepipost now labeled under its current name, Netcore.
-Small polish on the in-email "Wrong detection?" report.