What is MailViewr and how do I use it?

MailViewr's a free online tool for testing HTML emails across clients like Outlook, Gmail, Apple Mail. Paste code, preview renders instantly—no account needed.

Does MailViewr replace paid tools like Litmus?

For indie devs and one-offs, yes—core previews without $99/month. Teams might want Litmus' analytics, but MailViewr nails the basics.

Why do my HTML emails break in Outlook?

Outlook uses Word's engine, ignoring flexbox, modern CSS. Use tables, inline styles—MailViewr shows fixes before send.

🌐 Frontend & Web

Outlook Just Butchered Your Perfect HTML Email—Here's the Free Tool That Stops It

Your flexbox masterpiece crumbles in Outlook. One dev's rage quit birthed MailViewr—a free tester that mimics real email hell without the enterprise price tag.

DevTools Feed Apr 03, 2026 3 min read 12 views

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MailViewr interface showing broken HTML email render in Outlook vs perfect Chrome view

⚡ Key Takeaways

HTML emails demand tables and inline CSS due to outdated client rendering like Outlook's Word engine. 𝕏
MailViewr fills the free testing gap between browser previews and pricey enterprise tools. 𝕏
Email dev mirrors 1990s web hacks—MailViewr acts as the modern validator to democratize it. 𝕏

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#HTML emails #MailViewr #Outlook rendering #email testing

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