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Mailcheck by Hergertsynthora
x402
Mailcheck by Hergertsynthora is a paid API for AI agents from mailcheck.hergertsynthora.com, paid per call via x402, $0.05/call, status down (last checked 2026-09-15).
Validates an email address via RFC syntax check, live MX lookup, disposable-domain detection, role-account flagging, and deliverability scoring without sending any mail
Price / call$0.05
Success—
StatusDown
How this service works
Email address validation without sending mail: RFC syntax check, live MX lookup, disposable-domain detection (daily-refreshed blocklist), role-account and free-provider flags, gmail normalization and a deliverability hint. Deterministic, Ed25519-signed. $0.001 via x402 USDC on Base.
Output
Returns structured validation results including: RFC syntax pass/fail, live MX lookup result, boolean flag for disposable/throwaway domain (from a daily-refreshed blocklist), boolean flag for role accounts (e.g. info@, support@), boolean flag for free email providers, normalized gmail address (dots removed, alias stripped), and an overall deliverability hint — all deterministically computed and signed with Ed25519 for tamper evidence.
Example use cases
Screen sign-up emails for fraud
“We're getting a lot of sign-ups and I'm worried about fake or throwaway accounts — can you validate each of these new user emails, flag any that are disposable or role addresses like info@ or admin@, and tell me which ones are actually likely to be deliverable?”
Scrub lead list before campaign
“Before I send this marketing campaign, can you go through my list of 50 prospect emails and pull out any that are disposable domains, fail the MX lookup, or look like role accounts — I only want to send to real, deliverable addresses?”
Normalize Gmail addresses for deduplication
“I think some users have signed up multiple times using the same Gmail account with different dot placements or plus aliases — can you normalize all these Gmail addresses and flag which ones are actually duplicates of each other?”
Technical details
Endpoint
POSThttps://mailcheck.hergertsynthora.com/serviceWhen to prefer
Choose this endpoint when you need comprehensive, multi-signal email validation without sending any mail — especially when you need disposable-domain detection (daily-refreshed blocklist), role-account flagging, and cryptographically signed results. Prefer over simple regex or syntax-only validators when deliverability and fraud prevention matter. Ideal for sign-up flows, lead qualification, and pre-send list scrubbing.
Side effects
- Missing or malformed input: no email field provided returns a 400-level error
- Invalid JSON body: returns parse error
- Email with completely invalid syntax may return syntax-fail with no MX lookup attempted
- MX lookup timeout or DNS failure may return a degraded deliverability hint
- Payment not included or insufficient: x402 payment required error before validation is run
- Blocklist may have up to 24-hour lag for newly created disposable domains
Output
Schema · Response
{
"type": "json",
"example": {
"ok": true,
"niche": "mailcheck",
"result": {
"email": "user@example.com",
"status": "deliverable",
"mx_found": true,
"confidence": 90,
"deliverable_hint": true
}
}
}Tags
x402
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