Hello,
it is service to track emails similar to bananatag.com. Idea of project is to have service for email tracking without need to give access to my email to third-party company.

By default it designed to host on Google App Engine.

To track your email just add in content the following:

in HTML mode: <img src='link_to_tag'/>
in editor mode: add image of tag by link(!), not as content

Project on GitHub