Email Media Support Guide

This guide outlines how different email mailbox providers handle images, GIFs, and videos in marketing or transactional emails. It also includes best practices to ensure consistent rendering and fallback behavior.

Overview

Most email providers reliably support images and static graphics, but support for animated GIFs and especially videos varies widely. When sending rich media emails, always test across major clients and include fallbacks to ensure the message remains readable everywhere.

Images Support

Provider / Client	Inline Images (PNG/JPG)	SVG Support	Notes
Gmail (Web + App)	✔️ Full support	❌ Limited	Blocks images by default sometimes; loads after user action
Outlook Desktop (Windows)	✔️ Full support	❌ No	Outlook uses Microsoft Word rendering engine
Outlook Web (OWA)	✔️ Full support	❌ Limited	Better than desktop
Yahoo Mail	✔️ Full support	❌ No	Generally reliable
Apple Mail (iOS + macOS)	✔️ Full support	✔️ Yes	Best rendering engine overall
Samsung Mail	✔️ Full support	✔️ Partial	Good support
Thunderbird	✔️ Full support	✔️ Partial

Best Practices for Images

• Use PNG or JPEG for widest compatibility.

• Use alt text to improve accessibility and fallback.

• Keep images responsive using Fill Column option in the editor for auto height and width

• For responsive images in html use:

  img { max-width: 100%; height: auto; }

• Avoid relying on background images for critical content (Outlook desktop doesn’t support CSS backgrounds reliably).

GIFs Support

Provider / Client	GIF Support	Notes
Gmail (Web + App)	✔️ Yes	Loops automatically
Outlook Desktop (Windows)	⚠️ Partial	Plays only first frame (no animation)
Outlook Web	✔️ Full	Animations work
Yahoo Mail	✔️ Full
Apple Mail	✔️ Full
Samsung Mail	✔️ Full
Thunderbird	✔️ Full

Best Practices for GIFs

• Ensure the first frame contains key message, since Outlook Desktop will only show this frame.

• Compress GIFs to <1.5 MB to avoid slow loads.

• Prefer short loop animations.

Video Support

Native video playback inside email is supported only by a small subset of clients. Most providers block embedded videos for security reasons.

Provider / Client	Native Video in Email	Notes
Apple Mail (macOS + iOS)	✔️ Yes	Best support for HTML5 <video>
Samsung Mail	✔️ Yes	Good support
Outlook Desktop	❌ No	No embedded video support
Outlook Web	❌ No
Gmail (Web + App)	❌ No	Converts embeds to static thumbnail
Yahoo Mail	❌ No
Thunderbird	⚠️ Partial	Often blocks autoplay

Fallback Behavior in Most Clients

Where video is not supported:

• The HTML5 video is replaced with the fallback image inside the <video> tag

• Or the video block is removed entirely

Summary Table

Media Support by Email Provider

Email Provider	Images	GIFs	Video (Native)
Gmail	✔️	✔️	❌
Outlook Desktop	✔️	⚠️ (static only)	❌
Outlook Web	✔️	✔️	❌
Yahoo Mail	✔️	✔️	❌
Apple Mail	✔️	✔️	✔️
Samsung Mail	✔️	✔️	✔️
Thunderbird	✔️	✔️	⚠️

Best Practices for Video

• Always include a poster image (thumbnail).

• Always hyperlink fallback images to YouTube, Vimeo, or your landing page.

• Keep videos short and compressed (<10MB).

• Don’t rely on autoplay (largely unsupported).