Magic PHP Pixel Tracking: Track if an email message was viewed or opened

This package can be used to track if an email message was viewed or opened.

It takes an identifier string of an email campaign and returns an URL that should be used as URL of a pixel image to be inserted on the HTML data of an email message that is going to be sent to a certain user.

When the email is opened and viewed by the user, the email program may access the given URL to retrieve the image data.

The class is called to record the user access in a MySQL database table and it serves the data of a transparent image of size of 1 pixel of width and height.