How mail tracking works?

Question

whoreadme

is the web site that helps to track mail reader's location as well as it acknowledges when reader opens mail.

What is the concept of detection behind this?

Answer 1

From their FAQ,

WhoReadMe is embedded a transparent tracking image into your HTML e-mail. The image is assigned with unique ID and stored in WhoReadMe server. Once your recipient opens your e-mail, tracking image will be loaded from WhoReadMe server. Therefore, WhoReadMe is alerted to send you notification.

I am not quite taken with this :-)

Further,

In order to send a tracked e-mail, you need to login to WhoReadMe service, and send out your e-mail using http://whoreadme.com/send-e-mail.html. Alternatively, you can send the tracked e-mail from your own e-mail client by adding suffix ".whoreadme.com" to your recipient e-mail address. E.g.: [e-mail]

Hmm, this means whoreadme.com will forward my mail to gmail after 'fixing'!?

Will my recipient know that I am tracking my e-mail?
No, WhoReadMe tracking techniques is totally invisible to recipient

Really? with HTML tracking in the e-mail?

I received replies from my recipient, but WhoReadMe reported the e-mail is still waiting, why?
Some e-mail clients are blocking images by default. WhoReadMe inserts an invisible tracking image to every e-mail you sent. If your recipient blocks the image from loaded, the tracking will not working. Please make sure your recipient have added you to their safe list to bypass this problem.

Ah! Now you are talking...

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My short take on these technologies,

• Respect the receiver and let them reply at their leisure
  That is why e-mail is not a phone call
• Remember, every hop on the way is a potential weakness
  Read their privacy notes but remember many people do not even trust Google with their e-mail contents...