Gmail has improved their service to display pictures automatically without clicking that ‘display images below’ or ‘Always show images from <sender’s email address>’ button. This will apply to iOS app, Android app, and desktop site. Images are appear automatically and they (the images) are scanned for viruses and malwares.
If you prefer to authorize images send from sender you can choose the option ‘Ask before displaying external images’ or ‘Ask before displaying external content’ under the General tab in Settings.
This feature is available for desktop users starting from Thursday and will available with updates to iOS and Android app in early 2014.
Mobile Flaze Blog 