@emailens/mcp
MCP server for email compatibility analysis. Analyze, preview, diff, and fix HTML emails across 15 email clients — plus capture real screenshots and create shareable links with an optional API key.
Built on @emailens/engine. Also available as a GitHub Action.
Install
npx -y @emailens/mcp
Setup
Claude Desktop
Add to claude_desktop_config.json:
{
"mcpServers": {
"emailens": {
"command": "npx",
"args": ["-y", "@emailens/mcp"]
}
}
}
Claude Code
claude mcp add emailens -- npx -y @emailens/mcp
With API Key (optional — unlocks screenshots + sharing)
{
"mcpServers": {
"emailens": {
"command": "npx",
"args": ["-y", "@emailens/mcp"],
"env": {
"EMAILENS_API_KEY": "ek_live_..."
}
}
}
}
Get your free API key at emailens.dev/settings/api-keys.
Remote (no install)
Use the hosted endpoint — no npm or Node.js needed. API key required.
{
"mcpServers": {
"emailens": {
"url": "https://emailens.dev/api/mcp",
"headers": {
"Authorization": "Bearer ek_live_..."
}
}
}
}
Tools
Local Tools (no account needed)
preview_email
Full email compatibility preview — transforms HTML for 15 clients, analyzes CSS, generates scores, simulates dark mode, checks inbox preview and email size.
| Parameter | Type | Required | Description |
|---|---|---|---|
html | string | Yes | Email HTML source |
clients | string[] | No | Filter to specific client IDs |
format | enum | No | "html", "jsx", "mjml", "maizzle" |
analyze_email
Quick CSS compatibility analysis — returns per-client scores and warnings. Faster than audit_email when you only need CSS compatibility.
| Parameter | Type | Required | Description |
|---|---|---|---|
html | string | Yes | Email HTML source |
format | enum | No | Input format |
audit_email
Comprehensive quality audit — CSS compatibility, spam scoring, link validation, accessibility, images, inbox preview, size (Gmail clipping), and template variables.
| Parameter | Type | Required | Description |
|---|---|---|---|
html | string | Yes | Email HTML source |
format | enum | No | Input format |
skip | string[] | No | Checks to skip (e.g. ["spam", "images"]) |
fix_email
Generate a structured fix prompt for compatibility issues. Returns markdown with fix instructions that the AI can apply directly.
| Parameter | Type | Required | Description |
|---|---|---|---|
html | string | Yes | Email HTML to fix |
format | enum | No | Controls fix syntax |
scope | enum | No | "all" or "current" |
selectedClientId | string | No | Client ID for scoped fixes |
list_clients
List all 15 supported email clients with IDs, names, engines, and dark mode support.
diff_emails
Compare two email HTML versions — shows score changes, fixed issues, and introduced issues per client.
| Parameter | Type | Required | Description |
|---|---|---|---|
before | string | Yes | Original email HTML |
after | string | Yes | Modified email HTML |
format | enum | No | Input format |
check_deliverability
Check email deliverability for a domain — SPF, DKIM, DMARC, MX, BIMI records with a score and actionable issues.
| Parameter | Type | Required | Description |
|---|---|---|---|
domain | string | Yes | Domain to check (e.g. "company.com") |
Hosted Tools (require EMAILENS_API_KEY)
capture_screenshots
Capture real email screenshots across 15 clients in real browsers. Screenshots are hosted on CDN.
| Parameter | Type | Required | Description |
|---|---|---|---|
html | string | Yes | Email HTML source |
format | enum | No | Input format |
clients | string[] | No | Filter clients |
modes | string[] | No | ["light"], ["dark"], or ["light", "dark"] |
title | string | No | Name for the preview |
Free plan: 30 previews/day. Sign up
share_preview
Create a shareable link. Recipients see the full analysis without an account.
| Parameter | Type | Required | Description |
|---|---|---|---|
html | string | Yes | Email HTML source |
title | string | No | Display title |
format | enum | No | Input format |
Requires Dev plan ($9/mo). Share links expire after 7 days (Dev) or never (Pro).
Supported Email Clients (15)
| Client | ID | Dark Mode | Notes |
|---|---|---|---|
| Gmail | gmail-web | Yes | |
| Gmail Android | gmail-android | Yes | |
| Gmail iOS | gmail-ios | Yes | |
| Outlook 365 | outlook-web | Yes | |
| Outlook Windows | outlook-windows | No | |
| Outlook Windows Legacy | outlook-windows-legacy | No | Deprecated Oct 2026 |
| Outlook iOS | outlook-ios | Yes | New in v0.4.0 |
| Outlook Android | outlook-android | Yes | New in v0.4.0 |
| Apple Mail | apple-mail-macos | Yes | |
| Apple Mail iOS | apple-mail-ios | Yes | |
| Yahoo Mail | yahoo-mail | Yes | |
| Samsung Mail | samsung-mail | Yes | |
| Thunderbird | thunderbird | No | |
| HEY Mail | hey-mail | Yes | |
| Superhuman | superhuman | Yes |
Development
bun install
bun run build
bun test
bun run typecheck
License
MIT