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Email Validation API (Syntax + MX DNS Check)
x402
Email Validation API (Syntax + MX DNS Check) is a paid API for AI agents from gateway.stride20k.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-10).
Validates an email address via RFC-style syntax checking and live MX-record DNS lookup, returning a deliverability flag, parsed domain, and sorted MX hosts — without storing data or verifying mailbox existence.
Price / call$0.005
Success—
StatusUnknown
How this service works
Email validation API: RFC-style syntax check plus live MX-record lookup (with RFC 5321 A-record fallback) over DNS-over-HTTPS — no third-party service, nothing stored. Returns parsed domain, sorted MX hosts, and a 'deliverable' flag meaning DNS will accept mail for the domain — it does NOT verify the mailbox exists. Use for lead cleaning, signup validation, and contact verification by agents. Cached up to 1 hour per address.
Output
Returns a JSON object with: a boolean syntaxValid (RFC syntax check), a boolean deliverable (true if domain has MX records or an A-record fallback per RFC 5321), the parsed lowercase domain, an array of MX host records sorted by preference, hasMx and aFallback booleans, plus metadata including whether the response was served from cache (up to 1-hour TTL) and the ISO 8601 timestamp of the upstream DNS fetch.
Example use cases
Clean prospect list before outreach campaign
“I have a spreadsheet of 500 contact emails from a recent trade show. Can you validate each one — check the syntax is correct and make sure the domains are actually set up to receive mail — so I don't waste time sending to dead addresses?”
Verify signup email before account creation
“A user just signed up with their work email. Before we create their account, can you quickly validate that the email is syntactically correct and that their domain's mail servers are actually configured to receive messages?”
Check domain deliverability for sales outreach
“We're launching an outreach campaign to companies in the tech sector. Can you verify a sample of their domain email addresses — make sure the syntax is valid and confirm their mail infrastructure is live so we know our messages will actually be deliverable?”
Technical details
Endpoint
GEThttps://gateway.stride20k.com/email/validate/:email?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need a fast, privacy-respecting email validation that combines RFC syntax checking with real DNS MX-record lookup in a single call, without relying on third-party enrichment services or storing data. Prefer it over pure regex validators when DNS deliverability matters, and over SMTP-level verifiers when you don't need (or want) actual mailbox probing. Ideal for lead cleaning, signup form validation, and pre-send contact verification in agent workflows.
Side effects
- Malformed email path param returns syntaxValid:false with deliverable:false and null domain
- Domain with no MX and no A record returns deliverable:false and aFallback:false
- DNS resolution timeout or DoH upstream failure may return an error response
- Cached responses up to 1 hour old may not reflect recent DNS changes
- Mailbox existence is never verified — deliverable:true does not mean the inbox exists
Tags
x402
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