DomainCanary Spf Preflight API
The Spf Preflight API from DomainCanary — 1 operation(s) for spf preflight.
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curl "https://apis.io/api/v1/apis/domaincanary-com:domaincanary-com-spf-preflight-api"
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OpenAPI Specification
openapi: 3.2.0
info:
title: DomainCanary free Spf Preflight API
version: 1.0.0
summary: Check a domain's email authentication and test SPF changes, with no key.
description: 'The free JSON API checks a domain''s DMARC, SPF and DKIM records and lists what to fix. It also compares a new SPF record with the one you publish today and lists the senders that would fail SPF under the new one. You don''t need an account or a key.
DomainCanary is a DMARC enforcement service that protects your domain from email spoofing without blocking your own mail. The calls run the same checks as the free tools on the site.
Calls share an allowance of 30 lookups per IP address with the free tools on the site. A domain check counts as 5 lookups, or 6 when it checks a blocklist. An SPF pre-flight counts as 2. Once you''ve used the allowance, the API answers 429 with a Retry-After header, and the count starts again 10 minutes after your last call.
AI assistants can run the same checks over MCP at https://domaincanary.com/mcp.'
termsOfService: https://domaincanary.com/terms
contact:
name: DomainCanary
email: contact@domaincanary.com
url: https://domaincanary.com/about
servers:
- url: https://domaincanary.com
tags:
- name: Spf Preflight
paths:
/api/v1/spf-preflight:
post:
operationId: spfPreflight
summary: Test a new SPF record before you publish it
description: Resolves the published SPF record and the proposed one against live DNS and compares them. The verdict is fail when the proposed record breaks SPF (more than 10 lookups, a term receivers do not read, +all) or when a sampled address that passes today would stop passing. A CI job can fail a pull request on it. Send no Authorization header. If you send one with a key that matches no account, the API answers 401.
externalDocs:
description: SPF change pre-flight
url: https://domaincanary.com/tools/spf-change-check
requestBody:
required: true
description: JSON of at most 64 KB.
content:
application/json:
schema:
type: object
properties:
domain:
type: string
description: The domain, as in example.com.
record:
type: string
maxLength: 4096
description: The SPF record you plan to publish, with at most 200 terms. Quotes copied from a DNS panel are fine.
required:
- domain
- record
example:
domain: example.com
record: v=spf1 include:_spf.google.com -all
responses:
'200':
description: The comparison and its verdict.
content:
application/json:
schema:
$ref: '#/components/schemas/Preflight'
'400':
description: The body is not valid JSON.
content:
application/json:
schema:
$ref: '#/components/schemas/Error'
'401':
description: You sent an Authorization header with a key that matches no account.
content:
application/json:
schema:
$ref: '#/components/schemas/Error'
'413':
description: The body is larger than 64 KB.
content:
application/json:
schema:
$ref: '#/components/schemas/Error'
'422':
description: The domain is not a domain name, or the record is missing or is not a usable SPF record. problem says what is wrong with the record.
content:
application/json:
schema:
$ref: '#/components/schemas/InputError'
'429':
description: Your IP address has used its allowance.
headers:
Retry-After:
description: Seconds to wait before you call again.
schema:
type: integer
minimum: 1
content:
application/json:
schema:
$ref: '#/components/schemas/Error'
'503':
description: The DNS lookup for the domain did not complete. Try again.
content:
application/json:
schema:
$ref: '#/components/schemas/Error'
tags:
- Spf Preflight
components:
schemas:
Preflight:
type: object
properties:
checked_at:
type: string
format: date-time
domain:
type: string
verdict:
type: string
enum:
- fail
- warn
- pass
- unchanged
description: 'fail: publishing breaks SPF or drops a sender. warn: some senders could not be checked. pass: no tested address loses its pass. unchanged: the same senders as today.'
lookups:
type: object
properties:
published:
type: integer
minimum: 0
proposed:
type: integer
minimum: 0
limit:
type: integer
minimum: 0
description: Receivers stop at this many DNS lookups and return permerror.
required:
- published
- proposed
- limit
additionalProperties: false
all:
type: object
description: The all term each record ends in, or null when it has none.
properties:
published:
type:
- string
- 'null'
proposed:
type:
- string
- 'null'
required:
- published
- proposed
additionalProperties: false
removed:
type: array
description: Terms whose ranges the proposed record no longer covers.
items:
type: object
properties:
term:
type: string
description: The SPF term, exactly as it appears in the record.
ranges:
type: array
items:
type: string
description: The address ranges under it.
ipv4_addresses:
type: integer
minimum: 0
ipv6_ranges:
type: integer
minimum: 0
traffic:
oneOf:
- type: 'null'
- type: object
properties:
messages:
type: integer
minimum: 0
senders:
type: integer
minimum: 0
last_seen:
type:
- string
- 'null'
format: date
required:
- messages
- senders
- last_seen
additionalProperties: false
description: Mail from these ranges in the account's DMARC reports. Null without a key.
required:
- term
- ranges
- ipv4_addresses
- ipv6_ranges
- traffic
additionalProperties: false
added:
type: array
items:
type: object
properties:
term:
type: string
description: The SPF term, exactly as it appears in the record.
ranges:
type: array
items:
type: string
description: The address ranges under it.
ipv4_addresses:
type: integer
minimum: 0
ipv6_ranges:
type: integer
minimum: 0
required:
- term
- ranges
- ipv4_addresses
- ipv6_ranges
additionalProperties: false
lost:
type: object
properties:
ipv4_addresses:
type: integer
minimum: 0
ipv6_ranges:
type: integer
minimum: 0
required:
- ipv4_addresses
- ipv6_ranges
additionalProperties: false
floor:
type: object
properties:
applies:
type: boolean
description: True when the address counts are lower bounds.
terms:
type: array
items:
type: string
enum:
- a
- mx
- exists
- ptr
- macro
required:
- applies
- terms
additionalProperties: false
traffic:
description: Whether the removed ranges were compared with DMARC report traffic. Without a key, checked is false and reason is no-key.
oneOf:
- type: object
properties:
checked:
type: boolean
const: false
reason:
type: string
enum:
- no-key
- not-in-account
- not-verified
- no-reports
- stale-reports
required:
- checked
- reason
additionalProperties: false
- type: object
properties:
checked:
type: boolean
const: true
window_days:
type: integer
minimum: 0
description: Up to 90.
covered_days:
type: integer
minimum: 0
senders_truncated:
type: boolean
messages:
type: integer
minimum: 0
senders:
type: integer
minimum: 0
required:
- checked
- window_days
- covered_days
- senders_truncated
- messages
- senders
additionalProperties: false
findings:
type: array
items:
type: object
properties:
level:
type: string
enum:
- error
- warning
- notice
text:
type: string
required:
- level
- text
additionalProperties: false
url:
type: string
description: The SPF change pre-flight page on the site.
required:
- checked_at
- domain
- verdict
- lookups
- all
- removed
- added
- lost
- floor
- traffic
- findings
- url
additionalProperties: false
Error:
type: object
properties:
error:
type: string
description: What went wrong, in one sentence.
required:
- error
additionalProperties: false
InputError:
type: object
properties:
error:
type: string
problem:
type: string
enum:
- empty
- too-long
- control-chars
- not-spf
- too-many-terms
- term-too-long
description: Why the record was not read.
required:
- error
additionalProperties: false