{"schema":"draconic21.email_validate_availability.v1","available":true,"price_usdc":0.006,"source":"Live DNS (MX/A/AAAA/SPF/DMARC) + RFC syntax check + static disposable-domain list, no third-party vendor. Per-domain DNS reads cached 30min.","note":"POST { email }. Never sends mail; never opens an SMTP connection to the mailbox."}