What is it?
The Email HTML Checker finds code that email apps such as Gmail and Outlook remove or show wrongly. Paste your newsletter HTML, and each problem is listed with a plain explanation.
Who is it for?
Businesses sending newsletters, email marketers, developers building HTML emails, and anyone whose email looks perfect in a browser but broken in Gmail or Outlook.
How to use it
- Paste the HTML in Email HTML (newsletter or template).
- Read each finding and its fix.
- When you see No common email problems found., send a test email to Gmail and Outlook to confirm.
Why emails are different
Email apps are much stricter than browsers: Outlook for Windows uses Word to draw emails, and Gmail removes many CSS features. Tables and inline styles are old-fashioned but the most reliable way to build emails that look right everywhere.
Errors and how to fix them
- “Contains <script>: every email app removes JavaScript”
- “Uses flexbox or grid: Outlook for Windows ignores them. Use tables for layout”
- “External stylesheet <link>: most apps ignore it. Put CSS inline in style="" attributes”
- Background images: Outlook for Windows does not show them. Give a background colour as a fallback.
- No “unsubscribe” text found: bulk emails must offer one, and it helps avoid spam folders.
Questions people ask
- Does it send emails? No, it only checks the HTML you paste.
Open the tool: Email HTML Checker
Still stuck?
Contact support. Tell us which tool or page you were using, what you tapped, what you saw, and your phone or computer and browser (for example: Android phone, Chrome). We reply by email.
Questions, or an error not listed here?
Tell us in the comments: what you were doing, the exact message you saw, and your device and browser. We read every comment and add new fixes to this article.