Gmail recently made a fundamental change to how they serve images.
Gmail now serves images through a proxy and caching the image to speed up things and to reduce server load times. This is all great, however, this is a problem for ESP’s, as this will no longer reveal how many times and when a user opened up your email.
In order to avoid the gmail proxy and still be able to server the tracking image, simply edit the following file in your Oempro directory:
Scroll to the bottom of the file and comment the following line:
Then we add the following code after the commented line
header("Content-type: image/gif"); header("Content-length: 0"); $FileHandler = fopen(TEMPLATE_PATH.'images/trans.gif', "rb"); fpassthru($FileHandler); fclose($FileHandler);
This should fix the issue for now.
A special thanks to Andrew Bonar that explains more on this topic on his blog.