Mail7 Email Validation

What Mail7 Email Validation MCP server does

Mail7 Email Validation MCP server gives MCP-compatible AI clients four email operations. It can inspect one address, process a batch of up to 50 addresses, examine an SPF record, or audit a domain’s broader mail configuration. The service is accessed through the Mail7 API, with the MCP process acting as the client-facing interface.

Single-address validation combines syntax checks, MX lookup, disposable-domain detection, and a live SMTP mailbox probe. Batch validation returns a result for each address and summarizes the group as Valid, Not Valid, or Unknown. Unknown means the address could not be verified; it is not a second label for a bad address.

How it works

The server runs as a Node.js process and communicates with MCP clients over standard input and output. Each tool request is sent to Mail7 for checking, then returned to the assistant as tool output. Address validation can take several seconds because each address involves a live SMTP conversation rather than a local-only format check.

Validation tools provide structured fields when the client supports structured tool output. These fields can include the address, overall status, Boolean or null validity, format and MX results, SMTP status, disposable-domain status, and explanatory details.

The domain audit produces a compact A-to-F grade and identifies fixes for detected issues. A repeated call can request raw information for a selected section, including MX, SPF, DKIM, DMARC, MTA-STS, TLS-RPT, DNSSEC, BIMI, or the complete domain view.

Setup and configuration

Mail7 Email Validation MCP server requires Node.js 18 or newer. No package installation is needed for normal use: configure the client to run npx -y mail7-mcp and provide the MAIL7_API_KEY environment variable. An API key is available through the Mail7 account page.

MAIL7_API_KEY raises rate limits and enables full bulk validation. The server can run without it, but anonymous use is limited to five checks per minute and a 25-address free bulk sample. MAIL7_BASE_URL optionally replaces the default https://mail7.net/api endpoint.

For local development, the repository supports installing dependencies, building the project, and starting node dist/index.js; the built process speaks MCP over stdio.

Tools and capabilities

• validate_email: Checks one address for syntax, MX, disposable-domain status, and live SMTP mailbox response.
• validate_emails: Checks up to 50 addresses in one request and returns per-address results with a summary.
• check_domain: Audits MX, SPF, DKIM, DMARC, MTA-STS, TLS-RPT, DNSSEC, and BIMI, then assigns an A-F grade.
• check_spf: Reports an SPF record, its mechanisms, lookup count, and detected configuration problems.

Limitations and notes

Batch requests are intentionally capped at 50 addresses. For larger lists, submit successive chunks. Do not run bulk requests in parallel because the API serializes one bulk job per client.

SMTP checks are not instantaneous and can produce Unknown results. Catch-all mail servers and other conditions may prevent a definitive mailbox determination. Treat Unknown as unresolved rather than deleting or rejecting the address automatically.

The server uses stdio and requires an MCP client configuration. The README explicitly provides setup examples for Claude Code, Claude Desktop, Cursor, Windsurf, and Cline; other clients may use the same command-and-environment configuration shape.