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Google actually uses an image proxy to thwart tracking based on images.[1] http://googlesystem.blogspot.ca/2013/12/google-uses-proxy-to-load-gmail-images.html

• wtbob 12y ago
  Which won't work if it's a unique image (since it won't be in the proxy). And if it is a tracking image, it'll probably be unique.
  • ArchReaper 12y ago
    AFAIK they do this for all images. Not just commonly embedded images.
  • rlpb 12y ago
    If it's a unique image, then presumably Google reads it and pre-caches the image on receipt. So all you'll get from 1 pixel image is confirmation of email delivery, which is something you get with SMTP anyway. Of course if Google wait to cache the image when you actually read it, then this isn't true. But I'm prepared to give them more credit than that.
    • wtbob 12y ago
      > So all you'll get from 1 pixel image is confirmation of email delivery, which is something you get with SMTP anyway. You'll get a read-receipt, which SMTP doesn't offer.
• petercooper 12y ago
  Except it doesn't thwart tracking the actual open. Just the IP of the end user, etc: http://techcrunch.com/2013/12/12/gmail-open-rates/ http://techcrunch.com/2013/12/12/gmail-open-rates/