Email Verification: Syntax, MX, Disposable, Role and Optional SMTP

Keyless bulk email verification for list cleaning. The Actor checks practical syntax, domain mail routing (MX with implicit A/AAAA fallback), a built-in disposable-domain list, role-account patterns, and free-provider domains. It can optionally make one short SMTP recipient probe per address.

Honest scope

This Actor does not claim that an inbox exists, that a person owns it, or that a future message will be delivered. A domain with MX records can still reject a recipient, use a catch-all, block probes, or accept mail temporarily. SMTP acceptance is labelled as a best-effort protocol response, not proof of deliverability. SMTP timeouts, port-25 blocks, provider anti-enumeration, and catch-all behavior are returned as inconclusive.

No email is sent. No login, API key, residential proxy, mailbox access, or guessed address is used. DNS-over-HTTPS is used so cloud DNS behavior is consistent and bounded by a deadline.

Input

{
  "emails": ["person@example.com", "info@example.com", "bad@@example.com"],
  "checkSmtp": false,
  "smtpTimeoutMs": 5000,
  "maxConcurrency": 10
}

Duplicate addresses are normalized and verified once. With an empty emails array, the Actor returns one _sample: true row and charges nothing. Diagnostic and sample rows are never charged.

Output

Each completed address returns status (valid, risky, invalid, or unknown), confidence (a heuristic 0-100 score), syntax, domain, MX evidence, disposable and role flags, free-provider flag, and an optional SMTP object. valid means the address passed syntax and domain mail-routing checks; it is deliberately not a mailbox guarantee.

SMTP behavior

When checkSmtp is true, the Actor connects to the first MX host on TCP port 25 and sends EHLO, MAIL FROM, and RCPT TO, with an 8-second maximum per connection. It never sends a message. Cloud providers frequently block port 25 or mail providers deliberately prevent mailbox enumeration. In those cases the row remains valid/unknown based on MX evidence and the SMTP field says inconclusive; it is never upgraded to a deliverability claim.

Pricing proposal

Live pay-per-event price: $0.0006 per completed verification ($0.60 per 1,000). Invalid syntax rows are still completed checks and are billed once; empty/sample/diagnostic rows are not billed. This is below the lowest observed comparable at $0.70 per 1,000 while leaving a positive measured margin after Apify fees and direct DNS costs. No residential proxy is required.

Responsible use

Use only on addresses you are permitted to process. Respect privacy, anti-spam, data-protection, and recipient-domain policies. Results are list-cleaning signals, not consent or permission to send.

Local development

npm install --omit=dev --no-audit --no-fund
npm test
npm run check