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Overview

Run automated checks before send. Preflight runs on HTML compiled by Zinn: client previews, CSS compatibility, links, grammar, compliance basics, and AI spam and deliverability review in one dialog.
Preflight is available on paid plans only.

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How to Run Preflight

1

Open any email

Navigate to an email conversation or draft in the editor.
2

Click the Compatibility Check button

Click the Compatibility Check icon in the code view toolbar.
3

Review results

Preflight runs through 5 stages automatically. Results appear as each stage completes.

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What Gets Tested

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Client Previews

See how your email renders across popular email clients:
  • Web: Gmail, Yahoo, AOL, Outlook.com, iCloud, Hey, Superhuman
  • Desktop: Apple Mail, Mailbird, Zimbra
  • Mobile: iPhone, iPad, Android
Each client shows a preview image with a pass/fail status indicator.

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CSS Compatibility

Checks your email’s CSS against known email client support. Reports which clients have errors or warnings so you can fix compatibility issues before sending. Tests every link in your email:
  • Detects broken links (404 errors)
  • Checks response times
  • Flags unreachable URLs

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Grammar & Content

  • Spelling errors — catches typos and misspellings
  • Language detection — identifies the email language
  • Content quality — readability, tone, and complexity scoring
  • Brand voice — how well the content matches your brand (if configured)
  • Compliance — checks for unsubscribe link, sender identification

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Deliverability Score

  • Spam score — identifies spam trigger patterns
  • Category prediction — predicts whether the email will land in Inbox, Promotions, or Spam
  • Content signals — flags promotional, transactional, or engagement keywords
  • Recommendations — actionable tips to improve inbox placement

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AI-powered spam review

Preflight treats spam risk as a first-class check—not just DNS or list hygiene. The deliverability stage analyzes subject lines, body copy, link density, promotional language, and missing compliance elements (such as unsubscribe or sender identification) that often correlate with spam folder placement. When issues are found:
  1. Review red and yellow items in the Preflight panel.
  2. Click Fix with AI to generate an edit prompt that targets flagged issues.
  3. Apply changes in the editor and run Preflight again before sending or exporting.
Pair Preflight with CAN-SPAM checklist and What you can send so content and list quality both meet your standards. For client rendering details, see Email client compatibility.

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Reading Results

Each stage shows a status:
  • Green check — passed, no issues
  • Yellow warning — minor issues, review recommended
  • Red error — critical issues, fix before sending
The deliverability stage shows an overall score from 0–100% with a predicted delivery location.

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Fix with AI

Click Fix with AI to generate a prompt that addresses all flagged issues at once.

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Share Results

Click Share to generate a public URL for your preflight results. Useful for team reviews.

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Tips

  • Run preflight before every important campaign
  • Fix red issues first — they impact deliverability
  • Check the deliverability score to avoid the spam folder
  • Re-run after making changes to confirm fixes

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Programmatic Validation

Run preflight checks via the SDK, CLI, or MCP server. 
const { data } = await migma.validation.all({ html, conversationId });
The CLI supports individual checks: migma validate all|compatibility|links|spelling|deliverability.

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Next Steps

Export Options

Export your tested emails

Send a Campaign

Send your preflight-approved emails