Email Detective for Gmail: Identify ESPs & Check Authentication

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.

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WHAT IT DETECTS:

-200+ 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
-NEW: Inbox placement: where a sender's emails land in Gmail for other Email Detective users (inbox, Promotions or spam)
-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
-Your email content never leaves your browser
-Share anonymous meta data or opt out anytime in settings

*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.

© 2026 EmailTooltester. The extension, its detection patterns and data are proprietary (see the LICENSE file included in the package). Reuse requires written permission.

Changelog:

v2.1.237
- New: emails sent with Mailtrain and Cloudflare Email Service are recognized
- Improved: emails sent with Mautic and Oracle Eloqua are recognized in more cases

v2.1.233
- New: the popup shows when a countdown timer is built into the sending platform, for example "Countdown timer: built into Moosend"
- New: the popup notes images copied out of Gmail into an email ("Images copied from Gmail")
- New: newsletters sent by WordPress.com show that as their platform, and emails sent with TailoredMail are recognized

v2.1.216
- New: the popup flags emails signed with a weak DKIM key (shorter than the 2048-bit standard), read straight from the email's signature
- Email Detective now detects 200+ providers

v2.1.211
- Fixed: emails sent with Flodesk show as Flodesk again, instead of Amazon SES
- Improvements for bulk scans

v2.1.207
- New: spots text copied out of Slack ("Pasted from Slack"), and text copied out of Google Docs or Word now says "Pasted from" too
- Improved: Bulk Scan slows down as it goes and stops at 2,000 emails a day to avoid Gmail restrictions
- Fixed: Bulk Scan could get stuck scanning the same page over and over once your browser ran out of room for saved results
- Improved: emails sent with Dotdigital's transactional service and with Openstage, the fan platform for artists, are recognised
- Fixed: your ESP collection no longer counts more platforms found than it lists

v2.1.194
- New: warns when an email's unsubscribe link cannot work, because it points to nothing or to a placeholder like {{ unsubscribe }} that was never filled in, with the warning triangle on the badge
- New: spots text pasted from Word for the web, and notes leftovers from Google Docs; both lines show their logos
- Improved: emails sent with Maildroppa and Mailkit are recognised
- Added stars on the badge for emails containing traces of ChatGPT, Claude or Gemini
- New: the popup notes when an email still carries leftovers from Google Docs
- Improved: detection for emails sent with Maildroppa
- Improved activation screen.
- Switching off "Contribute anonymous data" in Settings now also stops the basic usage stats

v2.1.181
- Improved: emails sent with Stibee, Omnivery and two more are recognised
- Other improvements for research participants

v2.1.168
- Various detection improvements
- Emails sent with AhaSend are recognised
- Newsletters built with FeedOtter are recognised
- LiveIntent ads are recognised under Dynamic content

v2.1.160
- New: the popup notes when an email carries text pasted from Gemini, ChatGPT or other AI tools
- New: the popup shows when an email is tracked with Litmus or Validity
- Improved: Omnisend shops that send through Mailgun are recognised as Omnisend
- Fixed: long details under More details, such as a Return-Path address, no longer run outside the popup

v2.1.150
- Small bug fixes

v2.1.145
- Fixed: Bulk Scan tries again when an email's details don't load the first time, instead of leaving it unidentified and other improvements
- Improved: Pardot emails sent through Salesforce Marketing Cloud's servers are recognised as Pardot
- Improved: emails sent with FeedBlitz, Adobe Journey Optimizer and one more are recognised

v2.1.137
- Improved: newsletters sent with GetResponse from a company's own domain are recognised

v2.1.133
- New: see where a sender's emails land in Gmail (inbox, Promotions or spam), measured across Email Detective users, for senders we have enough data on. Free with sign-up
- Improved: the warning about a link that shows one address and goes to another now says why it matters: phishing emails often do this, so spam filters treat it as a warning sign

v2.1.128
- Fixed: several small detection improvements
- Old emails sent with Bronto, Oracle's shut-down ecommerce email platform, are recognised

v2.1.120
- Fixed: the risk checks read Japanese, Chinese, Korean, Thai, Hebrew and Arabic emails correctly.
- Mautic detection improved

v2.1.94
- New: hide the badges in Gmail with the X on any badge.
- Fixed: after the extension updates, an open Gmail tab no longer shows "No authentication data available" until you reload it
- Fixed: an email with no DMARC result, common on older mail, no longer shows as a DMARC fail
- Fixed: in Bulk Scan, a long platform name such as Mailchimp Transactional no longer runs into the Auth column

v2.1.75
- New: Risk factors. The popup now lists what a spam filter would score on an email: a sender name claiming a brand its address does not match, link text pointing somewhere different from the link, public link shorteners, and image-only emails with almost no text, invisible characters hidden in the sender name.
- The popup is tighter: delivery time now sits on the IP line, and the separate "Check reputation" row is gone
- Now identified: Tigramail, Zeta Global, and the MJML email builder

v2.1.15
- Fixed: on forwarded or replied-to mail, we could read details from the quoted message instead of the real one
- Fixed: a newsletter forwarded from a personal mailbox is now recognised as a forward
- Fixed: an email with no bounce address no longer shows the sender's own domain as one
- KlickTipp detection improved, ZeptoMail added

v2.1.13
- Several bug fixes

v2.1.12
- Fixed: if you use Gmail in Japanese, Chinese or Korean, the bulk scan stopped after the first page. It now works in every language
- We now record which language your mail client is displayed in, so we can tell when a change on Gmail's side affects people who don't use it in English. It is not linked to any email, and it is never shown publicly
- Other bug fixes

v2.1.9
- New senders recognised: Maropost, and an additional Marketo sending domain

v2.1.6
- Detects RichRelevance
- Fixed some detections being missed on emails with wrapped lines

v2.1.2
- Fixed the extension needing a page refresh after it updates
- Detects MoEngage, Shopware and Acrelia News

v2.1
- Detects RD Station
- You can now choose to contribute anonymous data after signing up
- Clearer DMARC results when a domain publishes two records
- Fixes to the "Check Email" button and the panel that opens from a badge

v2.0
- As it's a very popular feature Check (every) Email is now on by default when you register, and you can switch it off right from the badge
- Fixed emails from Proton Mail being reported as Postmark (both stamp a header with the same name)
- Fixed a reply being credited to the newsletter it was replying to
- Fixed "Got it" not closing the sign-up confirmation

v1.9.99
- The "Check Email" feature , which lets you analyse every email, is now part of signing up. If you already use it, it stays on
- Removed the experimental spam double-check (it wasn't really that useful)

v1.9.98.3
- Fixed the authentication warning disappearing when you opened an email
- The "check any email" badge now works on emails sent by a person

v1.9.98
- Fixed the detection panel closing straight after you opened it (this time for real).

v1.9.97
- Three more email platforms detected: SynXis, SMTP.com and one more (that I can't name, otherwise Chrome Web Store will say again that I am keyword spamming 🙈)
- Under the hood bug fixes

v1.9.95
- Logos now load instantly and privately as they are built into the extension, so it no longer asks an outside service for images while you read your email.
- Four more email platforms detected: Probance, MailUp and more
- Fixed: mail sent through Infobip was being credited to the wrong provider.
- Fixed: the details panel no longer closes on you when the badge refreshes.

v1.9.94
- Cheetah Digital added
- Smaller updates and corrections

v1.9.93
- Important update: now recognises nine more email tools: Mailrelay, Acumbamail, Webpower (and more). A friend forwarded a bunch of newsletters that weren't recognized - thank you.
- Fixed: Omnisend automated emails are now recognised.

v1.9.92
- New: Spam double-check (beta). Can be switched on in settings. Marks email in your spam folder that may not belong there. Feedback welcome!

v1.9.89
- Detects two more sending platforms (Action Network, Mapp)
- Other minor improvements

v1.9.88
- Shows which certificate a sender holds (VMC or CMC)
- Warns when it has expired or expires soon

v1.9.87
- Fixed the provider popup drifting out of place when scrolling
- Added detection for Qualtrics and improved it for Bloomreach
- Fixed Blackbaud detection

v1.9.86
- Fixed a false "broken authentication" warning

v1.9.85
- Improved detection for Mailmodo
- Fixed emails being labelled with the wrong service when their subject line happened to mention an email tool's name

v1.9.84
- Improved delivery-time measurement and wording

v1.9.83
- Important update: optional "Check Email" option on emails where no sending service is identified, so you can still see their SPF, DKIM and DMARC results (activate it in Settings → Undetected emails, off by default)
- Fixed: authentication details could show data belonging to a different email
- Added Knak HTML builder detection

v1.9.80
- Redesigned the activation screen
- Updated provider count to 170+

v1.9.79
- Fixed: clicking an ESP badge in the inbox list could show authentication details from a different email
- Fixed: the inbox list badge could stay on an earlier, less accurate result instead of updating
- Various under-the-hood improvements

v1.9.78
-Full support for Gmail's reading pane (vertical and horizontal split)

v1.9.77
-Added SendX and Zeta Global as detected ESPs
-Fixed a bug where forwarded newsletters could be misattributed to the wrong ESP
-Fixed a missing Brevo icon in the popup
-Added detection for red "might be dangerous" and yellow "be careful" warning banners

v1.9.76
-Added Nutshell and BonLoyalty
-Missing DMARC now shows a red X in the popup instead of a neutral dash

v1.9.75
-Detects Maileon and E-goi as ESPs, plus 4 more countdown-timer/live-content vendors: Sendtric, CountdownMail and more.

v1.9.74
-More accurate delivery-time measurement

v1.9.73
-More accurate detection for brands that use Intercom for both marketing and support emails.
-Fixed missing sender logos for some brands in the popup.
-Detection improvements

v1.9.72
-Detects forwarded emails, manual and auto-forwarded, across GMX/Outlook/Gmail/Yahoo/Apple Mail, and stops crediting the forwarder as the original sender.

v1.9.70
-Detection improvements

v1.9.69
-Adding some extra features under the hood. Collects some really interesting stats that will be shared very soon.

v1.9.64
-New detections: Haihaimail, Blastmail, Easypromos
-Removed the expired ActiveCampaign discount
-Activation screen in more languages

v1.9.62
-Added detection for ActionKit
-Behind the scenes tracking improvements

v1.9.59
-Fixed a bug where the authentication section could get stuck showing "no data available" instead of retrying and showing the real result.

v1.9.58
-Added TurboSMTP detection. DMARC warnings now show even when SPF/DKIM align.

v1.9.55
-Fixed a bug where the authentication section sometimes got stuck showing "checking" instead of the real result.
-Added discount links to the extension.

v1.9.53
-Behind-the-scenes improvements

v1.9.51
-Renamed Sarbacane / User.com / Positive Group to "Positive User" (2026 rebrand)
-Added Blackbaud detection

v1.9.49
-New detection for Inflection.io, Resend (when sent via Amazon SES), and IdoSell
-Forwarded emails now handled correctly: shows the original sender's SPF result and labels the message as forwarded, instead of showing a false "pass"
-Further detection improvements

Previous notes have been archived.