How does image blocking work in email clients?

Many email clients block images by default until the recipient clicks "display images" or adds the sender to their address book. This is a security and privacy measure-image loading can track opens and potentially execute exploits.

How it works: The client downloads email text but doesn't request external image URLs. Recipients see placeholder boxes or alt text. Once they click to load (or whitelist the sender), images appear. Outlook, corporate email systems, and privacy-focused clients commonly default to blocking.

Design as if images will be blocked. For a significant portion of your audience-especially B2B-images won't display on first view. Your email must communicate its core message through text alone. This isn't a worst-case edge case; it's a common scenario. Alt text, live text headlines, and text-based CTAs ensure your message survives image blocking.