<p>"Everyone knows their best customers are at Gmail, so that's a problem," said Quinn Jalli, senior vice president of digital marketing services at Epsilon, a digital marketing firm. "It's less clicks from the most affluent portion of society, so it has a disproportionate impact on the bottom line for retailers."</p><p>(Read more: Shoppers, beware: Time is running out for online)</p><p>Google announced Thursday that it would automatically show images in Gmail messages (before, Gmail required an extra click to display images, largely because malware could be embedded in the images.) Google now stores images on its own servers, where it screens them for safety, instead of on the senders' servers.</p><p>The flip side for retailers is that by storing images on their own servers, they received much more information about Gmail users who opened their messages, such as their locations. Now, they know someone opened an email but not much more.</p><p><a href="http://www.cnbc.com/id/101280580">Keep reading...</a></p><p>Read also:</p><p><a href="http://racked.com/archives/2013/12/18/store-holiday-emails-going-unopend-thanks-to-gmail-change.php">Store Holiday Emails Going Unopened Thanks to Gmail Change</a> (Racked National)</p><p><a href="http://www.zdnet.com/gmail-takes-further-steps-to-confound-marketers-7000024352/">Gmail takes further steps to confound marketers</a> (ZDNet)</p><p><a href="http://memeburn.com/2013/12/gmails-image-changes-will-affect-the-way-you-report-results-heres-how/">Gmail&#039;s image changes will affect the way you report results: here&#039;s how</a> (Memeburn)</p><p>Explore: <a href="http://news.google.com/news/more?ncl=d2zKzTjqVw3iREMthLHaJJU5B4HsM&ned=us">15 additional articles.</a></p>