Emailens MCP

What emailens/mcp MCP server does

emailens/mcp MCP server gives an MCP-compatible client tools for inspecting and improving email templates before sending them. It evaluates email HTML across 21 client profiles, including Gmail, Outlook, Apple Mail, Yahoo, Samsung, Thunderbird, Proton Mail, Fastmail, and others. Results include client-specific scores, compatibility findings, dark-mode analysis, inbox preview checks, and email-size checks.

The server accepts HTML directly and can also process JSX, MJML, and Maizzle. When a template format is supplied, it is compiled before analysis so the checks apply to the resulting email HTML. React Email is also listed as a supported input framework in the project description.

How it works

The local tools run through the npm package and do not require an account for compatibility analysis, audits, fixes, client listing, diffs, or DNS-based deliverability checks. An agent can start with analyze_email for a focused CSS review, use audit_email for a broader quality report, and then call fix_email to obtain structured Markdown instructions and format-specific fix snippets.

For HTML input, findings can include line, column, offset, and length information for the first occurrence, along with line numbers for additional occurrences. JSX, MJML, and Maizzle inputs are compiled first, so source positions are omitted rather than pointing to generated output. Findings can be narrowed to selected clients, and some reports support a full-detail mode or skipped checks.

Setup and configuration

Install the emailens/mcp MCP server with Node.js and npm:

npx -y @emailens/mcp

For Claude Desktop, register a server named emailens with npx as the command and -y @emailens/mcp as its arguments. The project also documents a hosted MCP endpoint at https://emailens.dev/api/mcp; that option requires an authorization bearer token and does not require a local npm installation.

Set EMAILENS_API_KEY when using hosted capabilities from a local configuration. The project states that API-key access unlocks screenshot capture and sharing. The free plan provides 30 screenshot previews per day, while share_preview requires the Dev plan listed at $9 per month.

Tools and capabilities

The emailens/mcp MCP server exposes these tools:

• preview_email transforms and evaluates an email across supported clients, including CSS scores, dark-mode simulation, inbox preview, and size checks.
• analyze_email returns grouped CSS compatibility findings and per-client scores, with optional client filtering and detailed output.
• audit_email checks compatibility, spam signals, links, accessibility, images, variables, overflow, contrast, design consistency, and Outlook VML structure.
• fix_email produces a structured fix prompt based on detected compatibility or structural problems.
• list_clients returns client IDs, names, rendering engines, and dark-mode support.
• diff_emails compares before-and-after versions and reports score changes, fixed issues, and new issues.
• check_deliverability looks up SPF, DKIM, DMARC, MX, and BIMI records for a domain.
• capture_screenshots renders light and dark variants in real browsers and hosts the resulting screenshots on a CDN.
• share_preview creates a link that lets recipients view the full analysis without an account.

Limitations and notes

Screenshot capture and share links are hosted features that require EMAILENS_API_KEY; sharing additionally requires the stated Dev plan. DNS deliverability checks use lookups and do not require an API key. Client filtering changes which findings are reported but does not change whole-email scores. The repository describes compatibility data for 255 CSS and HTML features, but support varies by email client, so a passing result for one client does not imply equivalent behavior elsewhere.