Free tool · Content

Email compatibility checker

Paste an HTML email and see which features break in Gmail, Apple Mail, Outlook, Yahoo and Samsung Mail, and what to do about each.

HTML

Compatibility score

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Paste HTML to start.

Questions

Where does the support data come from?: From the public rendering data the email community maintains (Can I email and client release notes), condensed to the features that break layouts most often. It is a guide, not a substitute for sending a test to real inboxes.
Is my HTML uploaded?: No. The check runs in your browser; nothing leaves the page.
What is the safest structure?: Tables for the outer layout, inline styles on every element, width attributes on images, a full font stack, and no dependency on media queries for the layout to be readable.

Sending with SMTPfast? A text version is generated for every HTML email automatically. Emails docs →