Public email-domain DNS readiness
Inspect one public ASCII domain's live MX, null MX, or implicit A/AAAA fallback with resolver/time/TTL evidence. Domain only; no email address, mailbox, deliverability, disposable/free-provider or role classification. x402 only.
standards · Operation ID: email-domain-readiness
Choose this operation when
- Inspect public-domain mail-routing DNS records with bounded live resolver evidence.
Outside this profile
- Full email validation, mailbox existence, SMTP delivery tests, disposable/free-provider/role classification, MX-host reachability, arbitrary DNS record types, private DNS, internationalized Unicode input, or guaranteed DNS freshness.
Exact release references
Static JSON contract · Markdown reference · Fixed example response
Complete input schema
{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"type": "object",
"properties": {
"domain": {
"type": "string",
"minLength": 3,
"maxLength": 254
}
},
"required": [
"domain"
],
"additionalProperties": false
}
Complete output-envelope schema
{
"type": "object",
"required": [
"operation",
"version",
"result",
"provenance"
],
"properties": {
"operation": {
"const": "email-domain-readiness",
"type": "string"
},
"version": {
"const": "0.29.0",
"type": "string"
},
"result": {
"$schema": "https://json-schema.org/draft/2020-12/schema",
"type": "object",
"properties": {
"profile": {
"type": "string",
"const": "public-email-domain-dns-v1"
},
"domain": {
"type": "string",
"maxLength": 253
},
"canonicalDomain": {
"type": "string",
"maxLength": 253
},
"status": {
"type": "string",
"enum": [
"mx_records",
"null_mx",
"implicit_mx",
"no_mail_route",
"nxdomain",
"inconsistent_mx"
]
},
"mxRecords": {
"maxItems": 64,
"type": "array",
"items": {
"type": "object",
"properties": {
"preference": {
"type": "integer",
"minimum": 0,
"maximum": 65535
},
"exchange": {
"type": "string",
"maxLength": 253
},
"ttlSeconds": {
"type": "integer",
"minimum": 0,
"maximum": 2147483647
}
},
"required": [
"preference",
"exchange",
"ttlSeconds"
],
"additionalProperties": false
}
},
"implicitAddresses": {
"maxItems": 128,
"type": "array",
"items": {
"type": "object",
"properties": {
"type": {
"type": "string",
"enum": [
"A",
"AAAA"
]
},
"address": {
"type": "string",
"maxLength": 45
},
"ttlSeconds": {
"type": "integer",
"minimum": 0,
"maximum": 2147483647
}
},
"required": [
"type",
"address",
"ttlSeconds"
],
"additionalProperties": false
}
},
"observations": {
"minItems": 1,
"maxItems": 3,
"type": "array",
"items": {
"type": "object",
"properties": {
"name": {
"type": "string",
"maxLength": 253
},
"type": {
"type": "string",
"enum": [
"MX",
"A",
"AAAA"
]
},
"status": {
"type": "string",
"enum": [
"NOERROR",
"NXDOMAIN"
]
},
"canonicalName": {
"type": "string",
"maxLength": 253
},
"observedAt": {
"type": "string",
"format": "date-time",
"pattern": "^(?:(?:\\d\\d[2468][048]|\\d\\d[13579][26]|\\d\\d0[48]|[02468][048]00|[13579][26]00)-02-29|\\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\\d|30)|(?:02)-(?:0[1-9]|1\\d|2[0-8])))T(?:(?:[01]\\d|2[0-3]):[0-5]\\d:[0-5]\\d(?:\\.\\d+)?(?:Z))$"
},
"resolver": {
"type": "string",
"const": "https://dns.google/resolve"
},
"resolverDnssecAuthenticated": {
"type": "boolean"
},
"records": {
"maxItems": 64,
"type": "array",
"items": {
"type": "object",
"properties": {
"name": {
"type": "string",
"maxLength": 253
},
"type": {
"type": "string",
"enum": [
"CNAME",
"MX",
"A",
"AAAA"
]
},
"data": {
"type": "string",
"maxLength": 512
},
"ttlSeconds": {
"type": "integer",
"minimum": 0,
"maximum": 2147483647
}
},
"required": [
"name",
"type",
"data",
"ttlSeconds"
],
"additionalProperties": false
}
},
"minimumAnswerTtlSeconds": {
"anyOf": [
{
"type": "integer",
"minimum": 0,
"maximum": 2147483647
},
{
"type": "null"
}
]
}
},
"required": [
"name",
"type",
"status",
"canonicalName",
"observedAt",
"resolver",
"resolverDnssecAuthenticated",
"records",
"minimumAnswerTtlSeconds"
],
"additionalProperties": false
}
},
"externalRequests": {
"type": "integer",
"minimum": 1,
"maximum": 3
},
"observedAt": {
"type": "string",
"format": "date-time",
"pattern": "^(?:(?:\\d\\d[2468][048]|\\d\\d[13579][26]|\\d\\d0[48]|[02468][048]00|[13579][26]00)-02-29|\\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\\d|30)|(?:02)-(?:0[1-9]|1\\d|2[0-8])))T(?:(?:[01]\\d|2[0-3]):[0-5]\\d:[0-5]\\d(?:\\.\\d+)?(?:Z))$"
},
"applicationDnsCache": {
"type": "string",
"const": "none"
},
"ttlPolicy": {
"type": "string",
"const": "remaining-resolver-answer-ttl-at-observation; replay-does-not-refresh"
},
"mailboxExistence": {
"type": "string",
"const": "not_checked"
},
"deliverability": {
"type": "string",
"const": "not_checked"
},
"mxHostAddresses": {
"type": "string",
"const": "not_checked"
},
"providerClassification": {
"type": "string",
"const": "not_checked"
}
},
"required": [
"profile",
"domain",
"canonicalDomain",
"status",
"mxRecords",
"implicitAddresses",
"observations",
"externalRequests",
"observedAt",
"applicationDnsCache",
"ttlPolicy",
"mailboxExistence",
"deliverability",
"mxHostAddresses",
"providerClassification"
],
"additionalProperties": false
},
"provenance": {
"type": "object",
"required": [
"inputSha256",
"outputSha256",
"deterministic",
"externalRequests"
],
"properties": {
"inputSha256": {
"type": "string",
"pattern": "^[a-f0-9]{64}$"
},
"outputSha256": {
"type": "string",
"pattern": "^[a-f0-9]{64}$"
},
"deterministic": {
"const": false
},
"externalRequests": {
"type": "integer",
"minimum": 1,
"maximum": 3
}
}
}
},
"additionalProperties": false
}
Fixed example
One accepted fixed example, not a custom-input trial. DNS evidence is an illustrative fixture, never a live lookup.
Example input
{
"domain": "example.com"
}
Example response
{
"operation": "email-domain-readiness",
"version": "0.29.0",
"result": {
"profile": "public-email-domain-dns-v1",
"domain": "example.com",
"canonicalDomain": "example.com",
"status": "null_mx",
"mxRecords": [
{
"preference": 0,
"exchange": ".",
"ttlSeconds": 300
}
],
"implicitAddresses": [],
"observations": [
{
"name": "example.com",
"type": "MX",
"status": "NOERROR",
"canonicalName": "example.com",
"observedAt": "2026-10-04T00:00:00.000Z",
"resolver": "https://dns.google/resolve",
"resolverDnssecAuthenticated": false,
"records": [
{
"name": "example.com",
"type": "MX",
"data": "0 .",
"ttlSeconds": 300
}
],
"minimumAnswerTtlSeconds": 300
}
],
"externalRequests": 1,
"observedAt": "2026-10-04T00:00:00.000Z",
"applicationDnsCache": "none",
"ttlPolicy": "remaining-resolver-answer-ttl-at-observation; replay-does-not-refresh",
"mailboxExistence": "not_checked",
"deliverability": "not_checked",
"mxHostAddresses": "not_checked",
"providerClassification": "not_checked"
},
"provenance": {
"inputSha256": "b9e2a80fa92f8d5059ab90188e0691ad6730871a209cc337c7565593597fbd58",
"outputSha256": "a7f5f263fc806b983907b619b6775fdeb681822afd1cea09f45cd835e53ac3a9",
"deterministic": false,
"externalRequests": 1
}
}
Bounds and precision
JavaScript IEEE-754 numbers; use strings for large integer IDs/exact decimals where the schema accepts strings. No lossless numeric parsing.
{
"global": {
"requestBytes": 131072,
"responseBytes": 524288,
"jsonDepth": 32,
"jsonNodes": 20000,
"requestsPerMinute": 60,
"paidAttemptsPerMinute": 20,
"idempotencyHours": 24
},
"operation": {
"queries": 3,
"queryTimeoutMs": 1500,
"totalTimeoutMs": 5000,
"resolverResponseBytes": 32768,
"recordsPerQuery": 64,
"outputBytes": 32768
}
}
Complete schemas, descriptions and cross-field validation may impose additional limits.
Proposed price and protocol definitions
{
"unit": "one successful operation call",
"proposedNominalUsd": "0.002",
"sixDecimalTokenBaseUnits": "2000",
"subscription": false,
"includesPayerWalletOrNetworkFees": false,
"liveQuoteVerified": false,
"condition": "Actual SDK challenge is authoritative only within the caller's explicit authorization; configured six-decimal token peg is an operator assertion, not a conversion guarantee."
}
Protocol definitions: x402. MPP is unsupported for this operation. Paid MCP execution is unsupported. All runtime readiness is not evaluated in this build.
API path templates, not endpoints on this documentation host
{
"x402": "/v1/x402/email-domain-readiness"
}
Required headers
{
"Content-Type": "application/json",
"Idempotency-Key": "random 16–128 character operation identifier"
}
Actual SDK challenge amount, asset, network, recipient and wallet costs must pass independent authorization. Preserve identical key, body, protocol and credential on retries; on PAYMENT_UNCERTAIN stop and reconcile.
Execution profile and provider conditions
{
"deterministic": false,
"externalRequests": "snapshot provenance counts original 1-3 queries; replay preserves that count and adds zero new queries",
"maxExternalRequests": 3,
"resultSnapshotPersisted": true,
"activation": {
"requiredOperatorAssertion": "DNS_PROVIDER_TERMS_REVIEWED=true",
"reason": "Commercial DNS wrapper/resale, upstream caching/redistribution and stored-replay retention require provider-terms review; this flag grants no permission",
"runtimeAssessment": "not-evaluated"
},
"fixedExampleIsIllustrativeSnapshot": true,
"requiresPayment": true,
"supportsMcpExecution": false
}
The live DNS profile transmits the supplied domain only to the fixed Google DNS resolver, at most three requests, and stores a bounded snapshot for exact replay. Provider review and payment configuration must be checked at runtime. Replay does not refresh observed DNS data.
Failure handling
- HTTP 400: Malformed JSON, missing/invalid idempotency key, or payment identifier mismatch Correct the request before payment
- HTTP 402: Payment challenge or rejected payment Use official protocol SDK; inspect payment outcome before another payment
- HTTP 409: Idempotency conflict, duplicate proof, or PAYMENT_UNCERTAIN Keep original key, body, and proof; reconcile uncertainty with operator; never blindly repay
- HTTP 413: Input or generated output too large Reduce input; no payment attempted for validation failure
- HTTP 415: Unsupported media type or compression Send uncompressed application/json
- HTTP 422: Schema or service-specific semantic validation failure Correct input using returned error code; no payment attempted
- HTTP 429: Request/payment-attempt rate exceeded Wait for rate limit window; preserve existing payment identity
- HTTP 503: Payment configuration/provider/state unavailable, or live DNS preparation failed before settlement Check readiness; DNS preparation failures may retry the identical key/body/credential only; uncertainty requires reconciliation
Declared requirements
Before any paid call, refresh the live operation contract and POST the complete bounded budgeted plan to the separate API's /preflight. Unknown requirements block selection; compatible preflight is not permission to spend.