Email Detective for Outlook: Identify ESPs & Check Authentication

Tracking since May 30, 2026.

Changelog

• Jun 12, 2026
  description

  See which ESP sent any email in Outlook. Detects 140+ 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 Outlook on the web 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.
  
  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
  
  ----
  Not using Outlook? We also have a version for Gmail: https://chromewebstore.google.com/detail/email-detective-for-gmail/jmflpchhakbogamlbfmlkglnpgfbhidl
  ----
  
  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)
  Works in your inbox list view for previously opened emails
  Your emails never leave your browser
  How to audit your own deliverability in seconds:
  
  Send yourself a campaign from your own email marketing service.
  Open it in Outlook, click the "Sent via" label, then "check authentication."
  You'll see SPF, DKIM, DMARC and BIMI status laid out cleanly. Anything missing or failing is flagged.
  
  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.
  
  Please note that the plugin also exists as a Gmail version (Email Detective for Gmail). 
  
  
  Changelog
  
  v1.0.23
  -Popup now matches the Gmail version: ESP favicons, a stacked inbox vs junk placement bar, and an Authentication tab.
  -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.
  
  v1.0.15
  -Further detection improvements (new ESPs added) 
  -Beefree SDK vs RGE Studio builder detection + the Postcards builder added
  -Other minor fixes
  
  v1.0.13 
  -Detection improvements. Previously detected labels won't disappear anymore.
  
  v1.0.10
  -Various bug fixes and faster detection
  
  v1.0.4
  -Minor improvements

  See which ESP sent any email in Outlook. Detects 140+ 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 Outlook on the web 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.
  
  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
  
  ----
  Not using Outlook? We also have a version for Gmail: https://chromewebstore.google.com/detail/email-detective-for-gmail/jmflpchhakbogamlbfmlkglnpgfbhidl
  ----
  
  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)
  Works in your inbox list view for previously opened emails
  Your emails never leave your browser
  How to audit your own deliverability in seconds:
  
  Send yourself a campaign from your own email marketing service.
  Open it in Outlook, click the "Sent via" label, then "check authentication."
  You'll see SPF, DKIM, DMARC and BIMI status laid out cleanly. Anything missing or failing is flagged.
  
  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.
  
  Please note that the plugin also exists as a Gmail version (Email Detective for Gmail). 
  
  
  Changelog
  
  v1.1.0
  -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.
  
  v1.0.25
  -SPF/DKIM/DMARC/BIMI now check automatically when you open the popup on a detected email. No extra click needed.
  
  v1.0.23
  -Popup now matches the Gmail version: ESP favicons, a stacked inbox vs junk placement bar, and an Authentication tab.
  -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.
  
  v1.0.15
  -Further detection improvements (new ESPs added) 
  -Beefree SDK vs RGE Studio builder detection + the Postcards builder added
  -Other minor fixes
  
  v1.0.13 
  -Detection improvements. Previously detected labels won't disappear anymore.
  
  v1.0.10
  -Various bug fixes and faster detection
  
  v1.0.4
  -Minor improvements

• Jun 5, 2026
  description

  See which ESP sent any email in Outlook. Detects 140+ 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 Outlook on the web 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.
  
  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)
  Works in your inbox list view for previously opened emails
  Your emails never leave your browser
  How to audit your own deliverability in seconds:
  
  Send yourself a campaign from your own email marketing service.
  Open it in Outlook, click the "Sent via" label, then "check authentication."
  You'll see SPF, DKIM, DMARC and BIMI status laid out cleanly. Anything missing or failing is flagged.
  
  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.
  
  Please note that the plugin also exists as a Gmail version (Email Detective for Gmail).

  See which ESP sent any email in Outlook. Detects 140+ 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 Outlook on the web 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.
  
  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
  
  ----
  Not using Outlook? We also have a version for Gmail: https://chromewebstore.google.com/detail/email-detective-for-gmail/jmflpchhakbogamlbfmlkglnpgfbhidl
  ----
  
  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)
  Works in your inbox list view for previously opened emails
  Your emails never leave your browser
  How to audit your own deliverability in seconds:
  
  Send yourself a campaign from your own email marketing service.
  Open it in Outlook, click the "Sent via" label, then "check authentication."
  You'll see SPF, DKIM, DMARC and BIMI status laid out cleanly. Anything missing or failing is flagged.
  
  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.
  
  Please note that the plugin also exists as a Gmail version (Email Detective for Gmail). 
  
  
  Changelog
  
  v1.0.23
  -Popup now matches the Gmail version: ESP favicons, a stacked inbox vs junk placement bar, and an Authentication tab.
  -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.
  
  v1.0.15
  -Further detection improvements (new ESPs added) 
  -Beefree SDK vs RGE Studio builder detection + the Postcards builder added
  -Other minor fixes
  
  v1.0.13 
  -Detection improvements. Previously detected labels won't disappear anymore.
  
  v1.0.10
  -Various bug fixes and faster detection
  
  v1.0.4
  -Minor improvements

Permissions & access

Permissions

storagescripting

Host access

None declared

Screenshots