Comment on Ask HN: How does my email tracking service know WHO opened my email?Comments−bigiain3yYour email client sent three emails, with different "hidden image file" urls.The cheesiest version just makes the image url be something like:https://example.com/trackingpixel.png?email=dhbanes%40exampl...and rewrites that query parameter for each of the To: Cc: and Bcc: addresses.A real implementation will more likely use a UUID instead of just plonking the email address in there, and store that uuid -> email mapping sevrerside.−dhbanesOP3yThanks for your response.I'm using gmail and when I go to the gmail web interface, the sent email appears as a single email with two BCCs as expected.But, after more investigation it looks like you're right. My outgoing headers appear different than incoming if I send myself a test email.
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Your email client sent three emails, with different "hidden image file" urls.
The cheesiest version just makes the image url be something like:
https://example.com/trackingpixel.png?email=dhbanes%40exampl...
and rewrites that query parameter for each of the To: Cc: and Bcc: addresses.
A real implementation will more likely use a UUID instead of just plonking the email address in there, and store that uuid -> email mapping sevrerside.
Thanks for your response.
I'm using gmail and when I go to the gmail web interface, the sent email appears as a single email with two BCCs as expected.
But, after more investigation it looks like you're right. My outgoing headers appear different than incoming if I send myself a test email.