@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.

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.

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