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Overview

Send with 100% confidence. Migma’s Email Preflight previews your emails on 30+ real devices and email clients, with automated checks for links, grammar, brand voice, and compatibility.

30+ Real Devices

See exactly how emails render on actual devices

Automated Checks

Links, grammar, brand voice, spam score

Fix Before Sending

Catch issues before they reach inboxes
What makes this different: ChatGPT and other tools can’t show you how emails actually render. Migma uses real devices and inboxes to give you pixel-perfect previews.

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What Gets Tested

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Device & Client Rendering

Desktop Email Clients:
Gmail (Chrome, Firefox, Safari)
Outlook 2021/2019/2016 (Windows)
Outlook for Mac
Apple Mail (macOS)
Yahoo Mail
AOL Mail
 Mobile Email Clients:
Gmail App (iOS & Android)
Apple Mail (iPhone, iPad)
Outlook Mobile (iOS & Android)
Yahoo Mobile
Samsung Email
 Webmail:
Gmail Web
Outlook.com
Yahoo Web
ProtonMail
 Dark Mode:
All clients with dark mode support

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Automated Quality Checks

Checks for:
  • Spelling errors
  • Grammar mistakes
  • Punctuation issues
  • Capitalization consistency
  • Typos in subject line
Result: Suggestions for corrections
Analyzes:
  • Tone matching your brand
  • Terminology consistency
  • Writing style alignment
  • Professional vs casual appropriateness
  • On-brand messaging
Result: Score + recommendations
Evaluates:
  • Spam trigger words
  • Image-to-text ratio
  • Link density
  • ALL CAPS usage
  • Excessive punctuation!!!
Goal: Keep score under 5/10Result: Spam score with improvement tips
Checks:
  • Alt text on all images
  • Color contrast ratios (WCAG AA)
  • Semantic HTML structure
  • Screen reader compatibility
  • Heading hierarchy
Result: Accessibility report
Validates:
  • Touch target sizes (44px minimum)
  • Text readability on small screens
  • Layout reflow
  • Image scaling
  • CTA button accessibility
Result: Mobile-friendly score

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How to Run Preflight

1

Open Email in Editor

Navigate to any email conversation or draft
2

Click Preflight Button

Look for ”📋 Preflight” button in toolbar
3

Select Devices

Quick Options:
  • All devices (comprehensive)
  • Mobile only (faster)
  • Desktop only
  • Custom selection
Tip: Use “All devices” for important campaigns
4

Run Tests

Click “Run Preflight” - takes 30-60 seconds
5

Review Results

See screenshots from all devices plus automated check results
6

Fix Issues

Address any flagged problems
7

Re-test

Run preflight again to confirm fixes

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Reading Preflight Results

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Device Screenshots

What you see:
  • Grid View
  • Detail View
  • Side-by-Side
Thumbnail grid of all devices side-by-sidePerfect for:
  • Quick visual scan
  • Spotting layout issues
  • Comparing across clients
Click any thumbnail to enlarge

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Check Results Dashboard

Color-coded results:

🟢 Passed

All checks passed - ready to send

🟡 Warnings

Minor issues - review recommended

🔴 Failed

Critical issues - fix before sending
Example Results: 
✅ Links: 12/12 valid
⚠️  Grammar: 2 suggestions
✅ Spam Score: 3.2/10 (Good)
❌ Dark Mode: Text unreadable on dark background
✅ Mobile: Fully responsive
⚠️  Accessibility: 3 images missing alt text

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Common Issues & Fixes

Problem: White text on white background in dark modeFix:
/* Add to your email CSS */
@media (prefers-color-scheme: dark) {
  .dark-safe-text {
    color: #000000 !important;
  }
}
Or tell Migma: “Fix dark mode text visibility”
Problem: Spam score above 5/10Common causes:
  • Too many exclamation marks!!!!
  • ALL CAPS WORDS
  • Spam trigger words (FREE, URGENT, WINNER)
  • Too many links
  • No unsubscribe link
Fix:
  • Remove excessive punctuation
  • Use sentence case
  • Reduce link density
  • Add unsubscribe link
Problem: Images without alt textFix:
  1. Click each image
  2. Add descriptive alt text
  3. Benefits: accessibility + shows if images blocked
Problem: Email looks broken in Outlook 2016/2019Cause: Outlook uses Word rendering engine (limited CSS)Fix:
  • Use table-based layouts
  • Avoid flexbox/grid
  • Use inline styles
  • Tell Migma: “Make compatible with Outlook”
Problem: Text under 14px on mobileFix:
  • Increase font sizes for mobile
  • Use media queries
  • Or: “Increase mobile text sizes”

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Preflight Best Practices

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Essential Testing Guidelines

Always preflight before important campaigns
Test on key devices your audience uses (check analytics)
Fix red flags immediately - they impact deliverability
Address warnings for better user experience
Re-test after fixes to confirm issues resolved
Save successful emails as templates

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Dark Mode Optimization (Critical for Deliverability)

Case Study Finding: Emails with proper dark mode support show significantly higher inbox placement rates and better consistency across email clients.
Why Dark Mode Testing Matters:
  • Over 60% of users now prefer dark mode
  • Email clients automatically transform emails in dark mode—often breaking layouts
  • Proper dark mode implementation signals quality to email providers
  • Deliverability Impact: Our studies show dark mode-optimized emails achieve better inbox placement
Best Practices:
  • ✅ Always test dark mode on Gmail, Outlook, and Apple Mail
  • ✅ Check text contrast - ensure readability in both light and dark modes
  • ✅ Verify brand colors don’t wash out or become invisible
  • ✅ Test images and logos - some need dark mode variants
  • ✅ Review CTAs - buttons must be visible and clickable in dark mode
Migma automatically handles dark mode optimization, but preflight testing ensures it works perfectly across all clients.

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HTML Quality = Better Deliverability

Case Study Finding: High-quality HTML emails significantly outperform plain-text emails for inbox placement, contrary to popular belief.
Why Quality HTML Lands in Inboxes: Plain-Text Problems:
  • Plain-text mass emails are spam filter red flags (low effort = suspicious)
  • Minimal engagement signals (no time tracking, no click behavior)
  • Associated with low-quality cold outreach and spam
  • Result: Higher spam folder placement rates
Migma HTML Advantages:
  • Professional, well-structured HTML signals legitimate business communication
  • Better engagement metrics (time spent, clicks) send positive signals to providers
  • Clean code and email best practices trigger quality indicators
  • Result: Consistently higher inbox placement rates
What Preflight Validates:
  • Clean HTML structure (no spam-triggering patterns)
  • Proper email standards compliance
  • Professional design signals
  • Engagement-friendly layout
  • All factors that improve deliverability
Bottom Line: Use preflight to ensure your emails have all the quality signals that email providers reward with inbox placement.

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Advanced Features

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Scheduled Preflight

Auto-run preflight before scheduled sends:
  1. Schedule email send
  2. Enable “Preflight before send”
  3. If tests fail, send is paused
  4. Fix issues and reschedule
Prevents: Sending broken emails automatically

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Preflight Reports

Download comprehensive report:
  • All device screenshots (PDF)
  • Check results summary
  • Issue recommendations
  • Historical comparison
Use for: Client presentations, team reviews, compliance

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Custom Device Sets

Save device configurations: Example sets:
  • “My Audience” - based on your analytics
  • “Enterprise” - Outlook-heavy
  • “Consumer” - Gmail + Apple Mail
  • “Mobile-First” - Mobile devices only
Benefit: Faster testing with relevant devices

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Migma vs ChatGPT

FeatureMigma Email PreflightChatGPT
Actual Device Testing✅ 30+ real devices❌ No preview
Dark Mode Preview✅ Yes❌ No
Link Validation✅ Automated❌ Manual
Spam Score Check✅ Built-in❌ No
Grammar Check✅ Automated⚠️ Via prompt
Outlook Compatibility✅ Real Outlook tests❌ Can’t verify
Mobile Rendering✅ Actual devices❌ No preview

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Pricing & Limits

  • Free Plan
  • Basic Plan
  • Premium Plan
  • 5 preflight tests/month
  • 10 devices
  • Basic checks only

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Next Steps

Visual Editor

Edit emails visually before testing

Export Options

Export your tested emails

Send Emails

Send your preflight-approved emails

Templates

Use pre-tested templates

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Need Help?

Watch Tutorial

Preflight walkthrough video

Join Discord

Share preflight results

Contact Support

Get help with test results

API Docs

Automate preflight testing