Call it a security feature to protect your privacy or one that helps your emails load quickly, many email tracking applications use embedded images to report back if you have read a certain email or not. It is also used by spam emails. To circumvent this, Gmail by default does not display external content automatically. It gives you a choice by the way of two links just above your email.
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Gmail also authenticates genuine emails (for instance, if someone has sent you an email twice with images in them). You can also set an email from a trusted source to always display images by clicking on the second link in the above screenshot that says – Always display images from.
If you like to control both behaviors i.e. the display or non-display of images in Gmail, dive into Gmail Settings.
1. Click the gear icon in the upper right, and then select Settings.
2. Scroll to the External content section. Select Ask before displaying external content. Alternatively, you can select Always display external content.