I Built an MCP Server That Verifies Emails via DNS — Zero API Costs

#mcp #email #devtools #buildinpublic

Email verification APIs cost $0.01–$0.05 per check. If you verify 10K emails/month, that's $100–$500 down the drain.

I built Email Verify MCP — an open MCP server that does the same job using raw DNS lookups. Zero API fees.

How It Works

Instead of calling a paid API (AbstractAPI, ZeroBounce, NeverBounce), Email Verify MCP:

Resolves MX records — does the domain accept mail?
Checks SMTP handshake — does the inbox exist? (catch-all detection)
Validates syntax + disposable domain blacklist
Returns a confidence score

All through DNS and a lightweight SMTP probe.

Install in 10 Seconds

npx @rumblingb/email-verify-mcp

Add to your Claude Desktop / Cursor / Copilot config:

{
  "mcpServers": {
    "email-verify": {
      "command": "npx",
      "args": ["@rumblingb/email-verify-mcp"]
    }
  }
}

What You Get

MX record resolution — checks domain mail acceptance
SMTP verification — confirms inbox existence without sending email
Catch-all detection — flags domains that accept everything
Disposable domain blacklist — blocks temp mail addresses
Syntax validation — RFC 5322 compliant
Confidence scoring — 0–100 scale

Why This Matters

Every AI agent workflow eventually needs to verify emails — signups, lead enrichment, notifications. Paying per-API-call for a DNS lookup is unnecessary overhead.

The MCP protocol makes this pluggable into any AI agent. One npx command and your agent can verify emails natively.

Buy Once, Use Forever

One-time purchase at buy.stripe.com/aFadRb2z56ZKaU00wz1oI1l. No subscriptions, no usage caps.

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mcp #email #devtools #buildinpublic #agentpay

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