Prior to December 2013, users had to approve to see images in emails, which acted as a security measure. This changed in December 2013, when Google, citing improved image handling, enabled images to be visible without user approval. Images are now routed through Google's secure proxy servers rather than the original external host servers. "MarketingLand" noted that the change to image handling means email marketers will no longer be able to track the recipient's IP address or information about what kind of device the recipient is using. However, "Wired" stated that the new change means senders can track the time when an email is first opened, as the initial loading of the images requires the system to make a "callback" to the original server.