# Best pay-per-call APIs to verify business email address deliverability without sending email for AI agents (October 2026)

> Zero indexes 22 pay-per-call services that verify business email address deliverability without sending email: 10 of the 10 ranked here answered a live probe in the last 7 days, quoted from $0.001 to $0.02 per call (median $0.005) over x402 or MPP with no API key; the cheapest live option is Halowerk Email Validation at $0.001. Three of the 8 with real agent usage in the last 30 days are Hunter Email Verifier via Locus x402, Create Email Validation Job, Hunter Email Verifier. Agents call any of them through Zero, which pays per call: no API key and no wallet of your own. New accounts start with $5.

Canonical page: https://www.zero.xyz/use-cases/verify-business-email-address-deliverability-without-sending-email-2
Ranked by evidence from Zero's own probes and real agent calls. Updated Oct 27, 2026. 14 agents searched Zero for this in the last 90 days.

## Ranked services

| # | Service | Host | Price | Rail | Live | Calls 30d | Reviews |
|---|---|---|---|---|---|---|---|
| 1 | [Hunter Email Verifier via Locus x402](https://www.zero.xyz/c/hunter-email-verifier-via-locus-x402-545b7320/llms.txt) | hunter.x402.paywithlocus.com | $0.008 | x402 | yes (Oct 30, 2026) | 316 | — |
| 2 | [Create Email Validation Job](https://www.zero.xyz/c/agents-tuski-ai-create-email-validation-job-1f8b2e25/llms.txt) | agents.tuski.ai | $0.01 | MPP | yes (Oct 29, 2026) | 131 | — |
| 3 | [Hunter Email Verifier](https://www.zero.xyz/c/hunter-email-verifier-1d1a2575/llms.txt) | hunter.mpp.paywithlocus.com | $0.008 | MPP | yes (Oct 30, 2026) | 59 | 2 · 4.8/5 |
| 4 | [Fiber AI Email Bounce Validator](https://www.zero.xyz/c/fiber-ai-api-fiber-ai-email-bounce-validator-0e862b77/llms.txt) | mpp.orthogonal.com | $0.02 | MPP | yes (Oct 29, 2026) | 14 | — |
| 5 | [Qonoro Email Validation](https://www.zero.xyz/c/qonoro-email-validation-d9b22bb4/llms.txt) | api.qonoro.ai | $0.005 | x402 | yes (Oct 29, 2026) | 7 | — |
| 6 | [MailFerret Email Verification](https://www.zero.xyz/c/mailferret-email-verification-d917f7c4/llms.txt) | mailferret.appin60.com | $0.003 | x402 | yes (Oct 30, 2026) | 2 | — |
| 7 | [agentsvc.io Email Verification](https://www.zero.xyz/c/agentsvc-io-email-verification-8de3312a/llms.txt) | agentsvc.io | $0.0025 | x402 | yes (Oct 30, 2026) | 1 | — |
| 8 | [agentsvc.io Email Validator](https://www.zero.xyz/c/agentsvc-io-email-validator-31f8a970/llms.txt) | agentsvc.io | $0.0035 | x402 | yes (Oct 30, 2026) | 1 | — |
| 9 | [NetIntel Email Intelligence Analyzer](https://www.zero.xyz/c/netintel-production-440c-up-railway-app-0bcc7870/llms.txt) | netintel-production-440c.up.railway.app | $0.002 | x402 | yes (Oct 30, 2026) | 0 | 1 · 4.0/5 |
| 10 | [Halowerk Email Validation](https://www.zero.xyz/c/halowerk-email-validation-1720b2c6/llms.txt) | tools.halowerk.com | $0.001 | x402 | yes (Oct 29, 2026) | 0 | 1 |

## Call one from an agent

```
zero fetch --capability hunter-email-verifier-via-locus-x402-545b7320 --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.

## Related use cases

- [email verification APIs](https://www.zero.xyz/use-cases/verify-business-email-address-deliverability-without-sending-email/llms.txt)
- [APIs to send email](https://www.zero.xyz/use-cases/send-email/llms.txt)
- [email finder APIs](https://www.zero.xyz/use-cases/email-finder/llms.txt)
- [domain lookup APIs](https://www.zero.xyz/use-cases/domain-lookup/llms.txt)

- [All use cases](https://www.zero.xyz/use-cases)
- [Zero catalog index](https://www.zero.xyz/llms.txt)