How to Preview HTML Email Templates

HTML emails are notoriously tricky. Different email clients render the same HTML differently, and what looks perfect in your code editor might break in Gmail, Outlook, or Apple Mail. The first step in debugging is seeing how your template renders — and you can do that instantly without sending a single test email.

The problem with email HTML

Email HTML is stuck in the past. Most email clients don't support modern CSS like flexbox, grid, or even reliable margin behavior. You're often working with tables, inline styles, and conditional comments for Outlook. This makes it critical to preview frequently as you build.

How to preview email templates with HTML Viewer Cat

1. Open the editor
2. Paste your email HTML into the left panel
3. The preview updates immediately — you'll see the rendered email on the right
4. Click the phone icon (375px) to see how the email looks on mobile
5. Click the tablet icon (768px) for tablet view
6. Use fullscreen mode to see the email at full scale

Tips for email template testing

• Test at 375px width first — most emails are read on mobile, so start with the smallest viewport
• Use inline styles — many email clients strip <style> blocks, so inline styles are more reliable
• Keep it simple — single-column layouts work best across clients. Multi-column designs are prone to breaking
• Test with real content — dummy text hides problems. Use actual copy, images, and links to catch issues early
• Check your links — a common mistake is forgetting https:// in href attributes

Example: simple email template

Here is a minimal responsive email template you can paste into the editor:

<div style="max-width:600px; margin:0 auto;
  font-family:sans-serif; color:#333;">
  <h1 style="color:#1a1a1a;">
    Welcome!
  </h1>
  <p style="line-height:1.6; color:#666;">
    Thanks for signing up. Click the button
    below to get started.
  </p>
  <a href="https://example.com"
    style="display:inline-block; padding:12px 24px;
    background:#007bff; color:#fff;
    text-decoration:none; border-radius:4px;">
    Get Started
  </a>
</div>