title: Mail marketer - avoid google image proxy to detect devices
body: <p>I'm trying to detect the devices that open my newsletter parsing the user-agent that request my 1x1 tracking image. The problem is that Gmail save all of the images in his storage and the user agent is always "Mozilla/5.0 (Windows NT 5.1; rv:11.0) Gecko Firefox/11.0 (via ggpht.com GoogleImageProxy)", this if the opener is from the gmail app and when is from the desktop interface. </p>
  
  <p>Now the question is, there's a way to tell Google avoiding to save the image in the newsletter? Maybe there's a custom header in the mail?</p>
  
  <p>Or maybe there are other solutions for detecting the tipology of the devices that open newsletter from gmail official interface?
  Thanks to all.</p>
  
  <p>Yuri </p>