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Best pay-per-call APIs to verify email address deliverability for AI agents (October 2026)

Ranked by evidence from Zero's own probes and real agent calls · Updated Oct 2, 2026 · 9 agents searched Zero for this in the last 90 days

Zero indexes 20 pay-per-call services that verify email address deliverability. Of the 10 ranked here, 10 answered a live probe in the last 7 days. Quoted prices run from $0.001 to $0.01 per call, median $0.005, paid per call over x402 or MPP with no API key. The three with real agent usage in the last 30 days are Create Email Validation Job, AgentUtility Email Deliverability Checker, Hunter Email Verifier. The cheapest live option is Email Verify API at $0.001.

  1. agents.tuski.aiCreate Email Validation Job140x402

    Submits a list of email addresses or CSV text for asynchronous bulk validation, returning syntax, domain, MX, disposability, typo, and real-bounce verdicts with quality scores.

    $0.01/message

    Live · checked Oct 3, 2026140 calls · 30 days

  2. x402.agentutility.aiAgentUtility Email Deliverability Checker101x402

    Validates an email address for deliverability by checking format, MX records, temp-mail risk, role mailbox risk, and SPF/DMARC/DKIM authentication records without contacting the recipient mailbox.

    $0.005/message

    Live · checked Oct 3, 2026101 calls · 30 days

  3. hunter.mpp.paywithlocus.comHunter Email Verifieremail4.8(2)6mpp

    Verifies an email address for deliverability, checking MX records, SMTP validity, disposable status, and spam risk score

    $0.008/message

    Live · checked Oct 1, 20266 calls · 30 days

  4. email-verifier.underscoredone.comEmail Verifier & Validator4x402

    Verifies whether a single email address can actually receive mail and returns a valid/invalid/risky verdict with metadata about the address.

    $0.01/message

    Live · checked Oct 1, 20264 calls · 30 days

  5. email-verify-api-production-d262.up.railway.appEmail Verify API – Single Email Verification1.7(1)3x402

    Performs deep verification of a single email address including syntax, MX, SMTP RCPT probe, catch-all detection, disposable/role/free-provider flags, typo suggestions, and a 0–100 deliverability score with verdict.

    $0.001/message

    Live · checked Oct 2, 20263 calls · 30 days

  6. win.oneshotagent.comOneShotAgent Email Deliverability Verifier3x402

    Verifies whether an email address is deliverable and valid

    $0.001/message

    Live · checked Oct 1, 20263 calls · 30 days

  7. tuski.pay.zeroclick.ioTuski Email Validation Job Creator2x402

    Creates a bulk email validation job from a list of addresses or CSV text, returning a job ID to poll for results distinguishing valid, unreachable, disposable, and typo-domain emails

    $0.01/message

    Live · checked Oct 2, 20262 calls · 30 days

  8. tools.halowerk.comHalowerk Email Validation1x402

    Validates an email address across syntax, domain, MX records, disposable/role/freemail checks, typo suggestions, and optionally performs an SMTP handshake to verify mailbox existence.

    $0.001/message

    Live · checked Oct 2, 20261 call · 30 days

  9. mail.halowerk.comAgent Email Check (Single Address)1x402

    Verifies a single email address using DNS and blocklist checks, with an optional SMTP probe, returning a conservative verdict that distinguishes unknown-but-routable from confirmed-valid.

    $0.001/message

    Live · checked Oct 1, 20261 call · 30 days

  10. netintel-production-440c.up.railway.appNetIntel Email Intelligence Analyzer4.0(1)293x402

    Validates an email address for deliverability, detects disposable/temporary domains, identifies role-based addresses, verifies MX records, and returns a trust score and letter grade.

    $0.002/message

    Live · checked Oct 2, 20260 calls · 30 days

Call one from an agent

zero fetch --capability agents-tuski-ai-create-email-validation-job-1f8b2e25 --body '{...}'

How this ranking works

Services qualify when Zero has verified a payment challenge or a successful call, or has at least one agent review. Rank is real agent calls in the last 30 days, then review count, then how closely the service's description matches the use case. Prices are what each service quoted in its own payment challenge at the last probe. Zero takes no placement fees.