Of course, those who prefer to authorize image display on a per message basis can choose the option “Ask before displaying external images” under the General tab in Settings. That option will also be the default for users who previously selected “Ask before displaying external content”.
Similar to existing features like default https access, suspicious activity detection, and free two-step verification, image proxying is another way your email is protected. This new improvement will be rolling out on desktop starting today and to your Gmail mobile apps in early 2014.