With SpyPig, you can easily find out when your email messages are opened and read by the recipients.
This is how SpyPig works. It generate an invisible GIF image per email address. When you compose a new email message inside Gmail or Hotmail or any other email program that can send rich HTML email, simply drag this tracking image into your message body.
Now send the message as usual and SpyPig will send you a notification email when the recipient opens your email. You’ll also get to know the recipient’s IP address, the approximate location, what browser they are using and other standard HTTP referral information.
When the recipient opens your email, SpyPig’s tracking image is downloaded on their computer and hence “email opened” action is recorded. Thus, image downloads should be enabled on the recipeint’s computer for the tracking to work.