Last week I shipped an MCP server that validates email addresses. No third-party APIs. No per-request fees. Just DNS lookups. It's called Email Verify MCP and it's my 62nd open-source tool on Smithery. How most email verification works (expensive) Services like ZeroBounce, NeverBounce, and Hunter charge $0.008–$0.01 per verification. If you're onboarding 100,000 users, that's $800–$1,000 just to check emails. These services resell DNS lookups with a markup. What I built instead Email Verify MCP does the same thing using raw DNS queries: MX record check — does the domain accept mail? SMTP handshake — can the mailbox actually receive? Disposable domain detection — flags temp emails from services like Mailinator Role account detection — catches admin@ , noreply@ , support@ Zero API costs. It runs locally or as an MCP server your AI agent can call.…