emailens/mcp

MCP server for email compatibility analysis. Analyze, preview, diff, and fix emails across 21 email clients, plus capture real screenshots and create shareable links with an optional API key.

Send HTML, MJML, Maizzle or React Email. Set format and the template is compiled before analysis, so what gets checked is the HTML your readers actually receive.

Why your assistant needs this: across the 298 CSS and HTML features we track, only 6 are fully supported in every major email client (see the data). Ask Claude to check your email before you send it.

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 app.emailens.dev/dashboard/api.

Remote (no install)

Use the hosted endpoint: no npm or Node.js needed. API key required.

{
  "mcpServers": {
    "emailens": {
      "url": "https://app.emailens.dev/api/mcp",
      "headers": {
        "Authorization": "Bearer ek_live_..."
      }
    }
  }
}

Tools

Local Tools (no account needed)

preview_email

Full email compatibility preview: transforms HTML for 21 clients, analyzes CSS, generates scores, simulates dark mode, checks inbox preview and email size.