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Agent Email Check – Batch Email Validation
x402
Agent Email Check – Batch Email Validation is a paid API for AI agents from mail.halowerk.com, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).
Validates up to 100 email addresses per call using DNS and list-based checks, with optional SMTP probing, billed per address.
Price / call$0.001
Success—
StatusUnknown
How this service works
Check up to 100 email addresses in one paid call, billed per address.
Output
For each submitted email address, the endpoint returns a verdict on validity and deliverability based on DNS and blocklist checks. If SMTP probing is enabled, a best-effort probe result is included — though without SMTP the verdict for routable addresses remains 'unknown'. Results cover up to 100 addresses per call, billed at 0.0006 USDC per address with a 0.001 USDC minimum.
Example use cases
Pre-send mailing list cleanup
“I have a list of 80 subscriber emails I collected from a form — can you validate all of them and tell me which ones are invalid or undeliverable before I send the newsletter?”
CRM contact hygiene sweep
“We just exported 95 contacts from our CRM. Can you run them through email verification with SMTP probing so we know which addresses are actually reachable?”
New user registration email check
“We're getting a lot of fake signups. Can you verify these 30 email addresses from today's registrations and flag any that look invalid or undeliverable?”
Technical details
Endpoint
POSThttps://mail.halowerk.com/email/batchWhen to prefer
Use this endpoint when you need to validate multiple email addresses in one round-trip and want to minimize cost through batching. It is ideal for list hygiene before email campaigns, CRM cleanups, or filtering sign-ups. Prefer this over single-address validators when you have 2–100 addresses to check. The optional SMTP probe is valuable when DNS-only results are insufficient, but be aware it is throttled and not retried.
Side effects
- Submitting more than 100 emails returns a validation error
- Submitting an empty array returns a validation error
- SMTP checks are heavily throttled and only attempted once per address — results may be absent or inconclusive
- Some domains block SMTP probes, leaving verdicts as 'unknown' even with smtp_check enabled
- Malformed email strings may be flagged as invalid without detailed reasoning
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| emails | array | Between 1 and 100 addresses. Billed at 0.0006 USDC per address with a 0.001 USDC minimum charge. |
| smtp_check | boolean | Ask for an optional SMTP probe. Off by default, heavily throttled, one attempt per target and never retried. Without it the verdict of a routable address stays "unknown". |
Tags
x402
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