email-verify ✉️
*Find out if an email address is real and deliverable — before you send.*
email-verify is a live email-verification service shipped two ways:
- an MCP server (
npx -y mailbox-verify-mcp) you plug into Claude, Cursor or any MCP agent, and - a pay-per-call HTTP API gated by x402 (USDC on Base) for autonomous agents — no sign-up, no API key.
It returns a VALID / RISKY / INVALID verdict with a 0–100 deliverability score and explained reasons.
What it checks
| Check | What it does | |---|---| | ✉️ Syntax | RFC-shaped local@domain, length limits, and common typos (gmial.com, hotmial.com, gmail.con). | | 📮 MX (live) | Live DNS lookup of the domain's mail servers — can it receive mail at all? Falls back to the A record (implicit MX) per RFC 5321. | | 🗑️ Disposable | Embedded catalog of hundreds of throwaway / temp-mail providers (Mailinator, 10minutemail, temp-mail, Guerrilla Mail, 1secMail …), including wildcard subdomains. | | 👥 Role-based | Shared function mailboxes (info@, admin@, support@, postmaster@) that hurt deliverability and don't map to a person. | | 🌐 Free provider | Flags consumer webmail (gmail/outlook/yahoo…) vs a business domain. | | 🎯 SMTP mailbox (deep) | Opens a live SMTP conversation to the real mail server up to RCPT TO: and quits — never sends DATA, so no email is ever delivered — to confirm the specific inbox exists. Plus catch-all detection (a domain that accepts every address). |
Everything is read-only. No email is ever sent.
Use it as an MCP server (free)
{
"mcpServers": {
"email-verify": { "command": "npx", "args": ["-y", "mailbox-verify-mcp"] }
}
}Tools:
verify_email— verify one address (deep: trueruns the live SMTP mailbox probe).verify_many— verify a batch (clean a list before a campaign).
Or connect over HTTP at POST /mcp.
Free HTTP API
GET https://email-verify-seven.vercel.app/verify?email=jane@example.com
GET https://email-verify-seven.vercel.app/verify?email=foo@mailinator.com # → RISKY (disposable)
GET https://email-verify-seven.vercel.app/verify?email=jane@gmial.com # → RISKY (domain typo)
GET https://email-verify-seven.vercel.app/verify_many?emails=a@x.com,b@y.comFree tier is rate-limited (30 / hour / IP) and runs every check except the live SMTP probe.
Pay-per-call (x402) — the deep tier
The /pro/* routes are gated by x402. Your agent pays $0.05 USDC per call automatically (Base); the paid tier runs the live SMTP RCPT-TO mailbox probe and lifts the batch cap to 50.
GET /pro/verify?email=<addr> # 402 → pay → deep result
GET /pro/verify_many?emails=a,b,c # up to 50 addressesSettlement goes on-chain straight to the operator wallet — the server holds no key.
A note on honesty about the SMTP probe
Many networks (including serverless egress) block outbound port 25. When the live SMTP probe can't connect, email-verify says so in the output (smtp_blocked) and degrades to MX + syntax + disposable + role signals rather than inventing a mailbox-exists result. The verdict reflects exactly what could and couldn't be confirmed.
Example output
{
"email": "jane@example.com",
"verdict": "VALID",
"score": 90,
"deliverable": true,
"reasons": [
{ "code": "has_mx", "severity": "info", "message": "Domain has 2 MX host(s); top: aspmx.example.com." },
{ "code": "smtp_accept", "severity": "info", "message": "Mailbox accepted by aspmx.example.com (SMTP 250). The inbox exists." }
],
"checks": { "syntaxValid": true, "hasMx": true, "disposable": false, "roleBased": false, "smtp": { "status": "deliverable" } }
}Why this exists
List cleaning and signup-fraud prevention are things businesses pay real money for. An LLM agent can't open a TCP socket to a mail server or carry a maintained disposable-domain catalog on its own — email-verify gives it that as one tool call.
Development
npm install
npm run dev:http # local HTTP server on :8080 (payments default ON; set X402_ENABLED=false to disable)
npm run dev:mcp # local stdio MCP server
npm run test:engine # deterministic offline testsLicense
MIT
