SpyPig is a free email tracking system which can send you a notification when your friends read your email. This special tracking system works with any web-based email program.
If you are using email client such as Microsoft Outlook with Microsoft Exchange Server, You can easily get notfied when your recipients read your email, but it is impossible for web-based email application such as Yahoo Mail, Gmail, or Live Mail to implement this feature.
SpyPig provide users a special image which include a tracking code. Users can then insert this tracking image in their email message, and they will get notified when others read the email.
To use SpyPig, simply provide them your email address, then type your message title (this is for better tracking so that you can know which email has been read). You can then choose your SpyPig image (if you don’t want your recipients know you are tracking the email, choose a blank image). After that, you can paste the tracking image on your email message and then send out the email. Currently, they limit the number of notification emails to 5 for each tracking code, which means you will only get 5 notifications even there are 10 people read your email.
SpyPig works fine with all email applications, both desktop clients and web-based email. But, you need to change some settings on your Microsoft Outlook in order for SpyPig to work. You can check it out here.
Note: Both you and your recipients must use HTML-format email so that they will download the tracking image when they open the email.