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Learn › Email Templates › Client Testing
Part 6 of 15 · Email Templates

Email Client Testing:
Test Across 50+ Clients & Devices

Email client fragmentation is real. Your template renders differently in Gmail, Apple Mail, Outlook, Yahoo, and Samsung Mail. Master a tiered testing strategy targeting high-volume clients, then test dark mode, mobile, and use automated testing tools.

Test Email Rendering Free Spam Tester

2026 Current

Email client market share in 2026: Gmail dominates (38-42%), followed by Apple Mail (20-25%), Outlook (15-18%), Yahoo (8-10%), and others. Mobile and dark mode represent 60%+ of opens.

Email Client Fragmentation Problem

No two email clients render HTML identically. This is the core challenge of email design. Gmail strips certain CSS properties. Outlook uses Microsoft Word rendering engine (on desktop). Apple Mail supports CSS media queries. Samsung Mail differs from Gmail on the same Android OS. Yahoo, AOL, and others have their own quirks.

Real-World Fragmentation Examples:

  • Gmail strips `
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