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. ---- Not using Gmail? We've just released an Outlook version: https://chromewebstore.google.com/detail/email-detective-for-outlo/lfhppcapafocegboaeaejkdamebobafo ---- 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: v2.1.246 - New: the popup shows when an email was made in SendGrid's own email editor v2.1.243 - Fixed: some emails sent with Mailchimp Transactional no longer show as Mailchimp - New: survey invitations sent with LimeSurvey are recognized - Changed: a DKIM key under 2048 bits is now called an "older key size", not a weak key: still accepted everywhere, but 2048 bits is the recommended size 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 GetRespons…