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    Email Testing Checklist: 13 Things to Check Before You Send

    EmailTestLab Team
    December 30, 2024
    4 min read
    email testingQA checklistemail marketingdeliverability

    Email Testing Checklist: 13 Things to Check Before You Send

    Sending an email without proper testing is like launching a rocket without a pre-flight check. One small mistake can derail your entire campaign. This comprehensive checklist covers the 13 essential tests every email marketer should run before hitting send.

    Why Email Testing Matters

    According to industry data, 87% of brands say email is critical to their business success. Yet, broken emails still slip through the cracks, damaging brand reputation and hurting conversions.

    Here's what you should check every single time:

    1. Subject Line Analysis

    Your subject line is your first impression. Here's what to verify:

    • Length: Keep it under 50 characters for mobile compatibility
    • Spam triggers: Avoid ALL CAPS, excessive punctuation (!!!), and spam words like "FREE" or "ACT NOW"
    • Emoji usage: One emoji max, and test rendering across clients
    • Personalization: Merge tags like {{first_name}} should render correctly

    Pro tip: Preview your subject line in Gmail, Outlook, and mobile to see exactly how it appears.

    2. Preview Text Optimization

    Preview text (preheader) is the second most important text in your email. Check for:

    • Length: 40-130 characters is ideal
    • Relevance: Should complement, not repeat, your subject line
    • Hidden text cleanup: Remove "View in browser" and other utility text from showing

    3. Email Size & Gmail Clipping

    Gmail clips emails larger than 102KB. When clipped, your email shows "[Message clipped] View entire message" which kills engagement.

    What to check:

    • Total HTML size (aim for under 80KB to be safe)
    • Image file sizes
    • Unnecessary code bloat

    4. Plain Text Version

    Many email clients and spam filters check for a plain text version. Ensure:

    • Your plain text version exists
    • It's readable and formatted properly
    • Links are included in full URL format

    5. Unsubscribe Link Detection

    CAN-SPAM and GDPR require a visible unsubscribe mechanism. Verify:

    • Unsubscribe link is present and working
    • It's easy to find (footer is standard)
    • List-Unsubscribe header is present for one-click unsubscribe

    6. HTML/CSS Validation

    Email HTML is notoriously finicky. Check for:

    • Valid HTML structure (proper closing tags)
    • No unsupported CSS properties
    • Inline styles for maximum compatibility
    • Valid <table> structures for Outlook

    7. Mobile Optimization

    Over 60% of emails are opened on mobile. Test for:

    • Responsive design that adapts to screen width
    • Touch-friendly button sizes (minimum 44×44px)
    • Readable fonts (14-16px minimum)
    • Single-column layouts that work on small screens

    8. Personalization Tokens

    Nothing kills credibility faster than "Hello {{first_name}}". Verify:

    • All merge tags render correctly
    • Fallback values are set for missing data
    • Dynamic content rules work as expected

    9. Dark Mode Support

    Dark mode can invert your colors unexpectedly. Check:

    • Logo visibility (use transparent backgrounds carefully)
    • Text remains readable
    • Button colors maintain contrast
    • @media (prefers-color-scheme: dark) rules work

    10. Spell Check

    Typos happen to everyone. Run spell check on:

    • Subject line
    • Preview text
    • Body copy
    • CTA buttons
    • Alt text for images

    11. Spam Score Analysis

    A high spam score means your email lands in junk. Check for:

    • Spam trigger words in content
    • Proper image-to-text ratio (aim for 40:60)
    • Clean HTML code
    • Valid authentication (SPF, DKIM, DMARC)

    12. Links & Images Validation

    Broken links and missing images are embarrassing. Verify:

    • All links are clickable and lead to correct URLs
    • Tracking parameters are properly formatted
    • All images load correctly
    • Alt text is present for accessibility
    • Image URLs use HTTPS

    13. Domain Authentication (SPF/DKIM/DMARC)

    Authentication is critical for deliverability. Ensure:

    • SPF record includes your sending domain
    • DKIM signature is properly configured
    • DMARC policy is set (at least p=none for monitoring)

    The Easy Way: Test Everything at Once

    Running all 13 checks manually is time-consuming. That's why we built EmailTestLab — a free email testing tool that runs all these checks in seconds.

    Simply paste your HTML, and get:

    • ✅ 13+ automated quality tests
    • ✅ 6 email client previews
    • ✅ Accessibility scoring
    • ✅ Spam score analysis
    • ✅ Dark mode verification

    Start Testing Free →

    Conclusion

    Email testing doesn't have to be complicated. By running through these 13 checks before every send, you'll catch issues before your subscribers do.

    Remember: Test once, send with confidence.

    Have questions about email testing? Contact us or try EmailTestLab free today.

    EmailTestLab Team

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