Email Preview

The Preview tab lets you see exactly how your email renders across 6 major email clients, with device and dark mode toggles.

Supported Email Clients

Gmail

Desktop and mobile rendering simulation with Gmail's specific CSS handling and image blocking behavior.

Outlook

Microsoft Outlook simulation including Word rendering engine quirks that affect layouts, backgrounds, and CSS.

Apple Mail

macOS and iOS mail app rendering with full CSS support and native dark mode adaptation.

Yahoo Mail

Yahoo's web and mobile mail rendering with their specific styling behaviors.

ProtonMail

Security-focused email client with unique rendering characteristics.

Thunderbird

Mozilla's desktop email client simulation.

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Device Views

Switch between device sizes to see responsive behavior:

Mobile

• Smartphone-sized viewport
• Shows how responsive design adapts
• Critical for 60%+ of opens

Tablet

• Tablet-sized viewport
• Medium breakpoint testing

Desktop

• Full-width desktop viewport
• Traditional email view

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Dark Mode Toggle

Instantly switch between:

• Light Mode - Standard light backgrounds
• Dark Mode - Simulated dark mode per client

Each email client handles dark mode differently:

• Apple Mail: Respects prefers-color-scheme media query
• Gmail: Partially inverts colors
• Outlook: Uses its own color inversion algorithm

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How It Works

Unlike screenshot-based tools that take 30+ seconds, EmailTestLab uses client-side CSS rendering:

1. Your HTML is processed with client-specific CSS transformations
2. Rendered in an iframe with appropriate styling
3. Device frames are applied for realistic preview
4. Instant switching - change client or mode in <50ms

Performance

• ⚡ 2-3 second test time (10x faster than screenshots)
• 🔄 Instant client switching - no waiting
• 💻 Browser-based - works on any device

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Inbox Preview

The separate Inbox Preview tab shows how your email appears in an inbox list:

• Subject line display
• Preview text (preheader)
• Sender name
• How it looks alongside other emails

This helps you optimize the "first impression" before someone opens your email.

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Tips for Preview

1. Check mobile first - Most opens happen on mobile
2. Toggle dark mode - Check logo visibility especially
3. Compare Outlook - It renders differently than web-based clients
4. Test all breakpoints - Mobile → Tablet → Desktop