Email - Open (Tracking)


Opening an email is an user action that shows engagement and is one of the email metrics.


The opened email are tracked with a invisible one-pixel image.

Ie when the email loads images, a HTTP get request is performed, sending a piece of information.

More see:


The tracking method is not working in the following situation:

  • The recipient formats their email in plain text.
  • The recipient's email client doesn't automatically download images.
  • The recipient's corporate filter strips away all images for incoming emails.



The referer identifies the URL of the page where the request originated. are unreliable for tracking because as the email clients may use link redirectors that will mask the source of the email, the referer will appear to come from the email provider and not the email.

Documentation / Reference

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