MailMode updates

Changelog

MailMode is evolving quickly. Here’s what’s changed recently.

v1.0.0

Initial Public Release

May 2026

Welcome to the first public version of MailMode — a lightweight email preview and dark mode testing tool built for email developers.

Core Previewing

Side-by-side light and dark mode email previews
Authored CSS dark mode simulation
Partial and full inversion dark mode simulations
Responsive viewport previews for:
- 375px Mobile
- 430px Large Mobile
- 768px Tablet
- 600px Email Standard
- 640px Email Wide
- 1440px Desktop
Dark mode comparison controls for checking authored CSS, selective inversion and aggressive forced dark behaviour

Supported Formats

Paste or upload HTML and HTM email files
MJML upload and browser-side rendering support
React Email preview support in safe/static mode
ZIP project uploads with local image asset handling
URL loading for publicly accessible email source files

Checks & Reports

Simple email health report with pass, warning and issue counts
Rendered HTML size and clipping-risk checks
Accessibility and image alt text checks
Subject and preheader preview checks
Link, tracking and UTM analysis
PDF report export for handoff or QA notes

Sharing & Safety

Shareable hosted preview links
Automatic 3-day share link expiry
Read-only shared previews with noindex metadata
Temporary upload and preview processing
Safe React Email preview sandboxing
Blocked dynamic runtime execution and unsafe JSX patterns

Launch Notes

MailMode is designed as a practical simulation tool, not an inbox-perfect replacement for live client testing
Dark mode behaviour still varies by email client, app version and device
Some React Email dynamic patterns are intentionally blocked in safe preview mode
The first public release focuses on fast previewing, simple checks and temporary sharing

Next

Coming Next

PDF export for Light/Dark previews
Improved health report analysis
Expanded healh report explanations
Expanded docs and examples
Performance improvements