DidTheyReadIt is a service that allows you to track the email you sent out. According to the website, you can tell whether people opened your email, how long it was open, etc.
Their website does not explain how they are able to do this, and I’m a little sceptical about how it could work. Is my system going to send an email back to them without me knowing it? I don’t think so! So what (and how) are they monitoring?
I’m not sure if this is scary or not, but it’s definitely annoying. If it’s doable and it becomes standard, I think you’ll find people setting up their email to automatically open on arrival.
I think it’s worth pointing out that in order to use their service, you have to send all of your email through them. Their Subscription Agreement says those emails will be “confidential in accordance with generally accepted standards of electronic mail usage” – what are “generally accepted standards”?
They have a free trial. If anybody tries it out, I’d be interested in learning how it works.
UPDATE:
Slashdotters discussed this. According to them, DidTheyReadIt embeds a small image in your email. When the user opens their email, the email client downloads the image from the DidTheyReadIt website, and they know the message has been opened. This wouldn’t be the most reliable of tools.
Image downloading can be turned off in most email clients.