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Agent Email Check (Single Address)
x402
Agent Email Check (Single Address) is a paid API for AI agents from mailcheck.netzhandwerker.de, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).
Validates a single email address using DNS and blocklist checks, with an optional SMTP probe for definitive deliverability verdicts.
Price / call$0.001
Success—
StatusUnknown
How this service works
DNS and list based verification. Never claims that a mailbox exists without evidence: without an SMTP probe the verdict for a routable address is "unknown", not "valid".
Output
Returns a verdict for the email address — either 'valid', 'invalid', or 'unknown' (if no SMTP probe was run on a routable domain) — along with DNS resolution status, blocklist match information, and whether the domain is routable. Without smtp_check=true, a routable address that hasn't been probed returns 'unknown' rather than 'valid'.
Example use cases
Pre-send lead validation
“Before I import this lead into my CRM, check if sarah.jones@acmecorp.com is actually deliverable — use the SMTP probe so I know for sure it's not just a routable domain with no real mailbox.”
Sign-up form abuse prevention
“A user just entered support@tempmail.org on our registration form — can you verify whether that email address is real and not on any blocklists?”
Bounce risk check before campaign
“I'm about to send a newsletter to newsletter@bigclient.com — do a DNS and SMTP check on it first so I can remove it if it's going to bounce.”
Technical details
Endpoint
POSThttps://mailcheck.netzhandwerker.de/emailWhen to prefer
Use this endpoint when you need fast, conservative email verification for a single address and want to avoid false positives — it explicitly returns 'unknown' rather than guessing 'valid' without evidence. Prefer it over bulk endpoints when checking a single address at a time, and enable smtp_check=true only when a definitive deliverability answer is required and the slight latency and throttling are acceptable.
Side effects
- Invalid email format returns an error or invalid verdict immediately
- SMTP probe throttled or unavailable for the target domain — verdict stays 'unknown'
- Domain does not exist in DNS — returns invalid
- Temporary DNS resolution failure may produce uncertain results
- SMTP check is one-attempt-only and never retried, so transient errors yield 'unknown' not 'valid'
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| string | The email address to check. | |
| 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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