Email Client Reference

Each email client uses a different rendering engine with different CSS and HTML support. Understanding these differences is key to building email templates that work everywhere.

O

Outlook Desktop (2007–2019)

Word/MSO engine

Uses Microsoft Word's HTML engine — the most restrictive client. No flex, no grid, no border-radius, no media queries.

O

Outlook.com / 365 Web

Blink engine

Browser-based; much more capable than desktop Outlook. Strips some CSS properties for security. No CSS variables or transforms.

G

Gmail (Web + Mobile)

Blink / WebKit engine

Strips <style> from <head> — all styles must be inline or in <style> in <body>. No CSS variables. No external stylesheets.

A

Apple Mail (macOS + iOS)

WebKit engine

Most permissive client — full WebKit engine. Supports flex, grid, animations, CSS variables, and WebP.

Y

Yahoo Mail

Blink engine

Blink engine with aggressive sanitization — stricter than Gmail. Strips SVG entirely, moves <style> out of <head>, no CSS variables.

S

Samsung Email (Android)

WebKit (Android) engine

Android WebKit with minimal sanitization — one of the most capable clients. Supports flex, grid, SVG, and dark mode. 360px mobile viewport.

⚠ General Email Pitfalls

Common mistakes that trip up developers across all email clients — images, fonts, dark mode, and more.