How to implement email tracking solution?

nginX has a module called empty_gif that generates a 1*1 pixel image. It is usually put at the end of campaign emails in order to track how many users have opened the email. The code for nginX is:

location = /empty.gif {
     empty_gif;
     expires -1;
     post_action @track;
 }

 location @track {
    internal;
     proxy_pass https://tracking-backend/track$is_args$args;
    proxy_set_header    x-ip     $remote_addr;
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection 'upgrade';
 }

The above code check if /empty.gif URL is requested, if answer is yes then serve the image and makes expires to -1 to not cache the image and finally using post_action which calls a sub request after the current request has been fininshed. The parameters you need to pass is put after the image link in email like:

https://www.example.com/empty.gif?token=SOMETHING_TO_TRACK

#nginx #email #empty_gif #email_tracking #pixel