Email Detective for Gmail: Identify ESPs & Check Authentication

See which ESP sent any email in Gmail. Detects 170+ providers and shows SPF/DKIM/DMARC 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. ---- Not using Gmail? We've just released an Outlook version: https://chromewebstore.google.com/detail/email-detective-for-outlo/lfhppcapafocegboaeaejkdamebobafo ---- WHAT IT DETECTS: -170+ 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 -Your email content never leaves your browser -Share anonymous meta data or opt out anytime in settings (registered users are opted out automatically) *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: v2.1.15 - 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, MailTimers, and Motion Mail App 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.