@emailens/cli

CLI tool for email compatibility analysis — preview how HTML emails render across 12 email clients (Gmail, Outlook, Apple Mail, Yahoo, Samsung, Thunderbird, HEY, Superhuman).

Install

npm install -g @emailens/cli

Or use with npx:

npx @emailens/cli analyze email.html

Commands

emailens analyze <file>

Analyze CSS compatibility and get per-client scores.

emailens analyze email.html
emailens analyze email.html --clients gmail-web,outlook-windows
emailens analyze email.html --json
cat email.html | emailens analyze -

emailens preview <file>

Full preview pipeline: transforms, analysis, dark mode simulation, and optional screenshots.

emailens preview email.html
emailens preview email.html --dark-mode
emailens preview email.html --screenshots --out ./screenshots
emailens preview email.html --json

emailens export <file>

Export a self-contained HTML or JSON report.

emailens export email.html -o ./report
emailens export email.html --json -o ./report
emailens export email.html --dark-mode --screenshots -o ./report

emailens fix <file>

Generate AI-powered fixes for email compatibility issues. Uses @emailens/engine analysis to build a structured prompt, then calls Claude to fix structural issues (table layouts, VML, MSO conditionals) that static snippets can't handle.

Requires ANTHROPIC_API_KEY environment variable and the optional @anthropic-ai/sdk dependency.

emailens fix email.html                           # Fix and print to stdout
emailens fix email.html -o fixed.html             # Write to file
emailens fix email.html --estimate                 # Show token estimate only (no AI call)
emailens fix email.html --clients outlook-windows  # Scope to one client
emailens fix email.html --json                     # Full JSON output with metadata
emailens fix email.html --max-tokens 8000          # Limit prompt size
cat email.html | emailens fix - --format jsx       # Pipe from stdin

| Flag | Alias | Description | |------|-------|-------------| | --format | -f | Input format: html, jsx, mjml, maizzle | | --clients | -c | Comma-separated client IDs to scope the fix | | --output | -o | Write fixed code to file instead of stdout | | --json | | Output as JSON (includes token estimates and metadata) | | --quiet | -q | Suppress spinners and decorations | | --estimate | | Only show token estimate without calling the AI | | --max-tokens | | Maximum input tokens for the prompt (default: 16000) |

emailens clients

List all 12 supported email clients.

emailens clients
emailens clients --json

Options

All file-processing commands share:

| Flag | Alias | Description | |------|-------|-------------| | --format | -f | Input format: html, jsx, mjml, maizzle | | --clients | -c | Comma-separated client IDs to filter | | --json | | Output JSON instead of terminal table | | --quiet | -q | Suppress spinners and decorations |

Preview and export add:

| Flag | Alias | Description | |------|-------|-------------| | --dark-mode | -d | Include dark mode simulation | | --screenshots | | Capture screenshots (requires BROWSERLESS_URL) | | --out | -o | Output directory |

AI Fixes

The fix command requires an ANTHROPIC_API_KEY environment variable and the @anthropic-ai/sdk package:

npm install @anthropic-ai/sdk
export ANTHROPIC_API_KEY=sk-ant-...

Use --estimate to check token usage before making an API call:

emailens fix email.html --estimate
#   Input tokens:    ~4,200
#   Output tokens:   ~5,400
#   Warnings:        23 (5 structural)

Framework Support

The CLI can compile React Email (JSX/TSX), MJML, and Maizzle templates to HTML before analysis. Format is auto-detected from file extension, or specify with --format.

emailens analyze newsletter.tsx              # Auto-detected as JSX
emailens analyze template.mjml               # Auto-detected as MJML
emailens preview email.html --format maizzle # Explicit format

Framework compilers are optional peer dependencies — install only what you need:

npm install sucrase react @react-email/components @react-email/render  # For JSX
npm install mjml                                                        # For MJML
npm install @maizzle/framework                                          # For Maizzle

Screenshots

Screenshots require a Browserless instance and playwright-core:

npm install playwright-core
export BROWSERLESS_URL=ws://localhost:3000
emailens preview email.html --screenshots --out ./screenshots

Piping

Read from stdin with -:

cat email.html | emailens analyze -
echo '<html><body>Hello</body></html>' | emailens preview - --json

License

MIT