Free & Open Source

Email Deliverability
Checker

Check SPF, DKIM, DMARC, MTA-STS, TLS-RPT & BIMI for any domain — free, instant, no signup

Press Enter or click Check — supports SPF, DKIM, DMARC, MTA-STS, TLS-RPT & BIMI

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Deliverability Score

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SPF

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DKIM

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DMARC

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MTA-STS

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TLS-RPT

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BIMI

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Features

Six checks. One scan.
Complete email auth audit

SPF, DKIM, DMARC, MTA-STS, TLS-RPT, and BIMI — the full suite of email authentication protocols, checked in one pass with a 0–100 deliverability score.

🛡️

SPF Analysis

Validates Sender Policy Framework records, checks +all/~all/-all mechanisms, DNS lookup limits, and deprecated ptr mechanisms.

🔐

DKIM Verification

Scans for DKIM public keys across 17 common selectors, validates key strength (1024/2048-bit), and detects test mode.

📋

DMARC Audit

Checks DMARC policy enforcement, pct tags, and reporting addresses (rua/ruf) — helping you move from monitoring to reject.

🔒

MTA-STS (RFC 8461)

Verifies MTA-STS DNS records and TLS policies, checking that receiving MTAs enforce STARTTLS connections to your domain.

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TLS-RPT (RFC 8460)

Checks TLS Reporting DNS records for SMTP TLS failure and success reporting, helping you monitor TLS compliance.

🏷️

BIMI Verification

Scans Brand Indicators for Message Identification records — your logo in inboxes — validating location and authority tags.

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Instant Results

No queues, no waiting. DNS lookups run in parallel and results return in under 2 seconds for most domains.

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REST API

Clean JSON API at /api/v1/check/{domain} — integrate deliverability checks into your CI/CD, dashboards, or onboarding.

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Open Source

Fully open-source under MIT license. Self-host or contribute at our Forgejo repo.

API Reference

Simple REST API

One endpoint, one request, full deliverability report. No authentication required — just hit the URL.

GET https://korpo.pro/api/v1/check/{domain}

cURL

Response

# Check a domain's email deliverability
curl https://korpo.pro/api/v1/check/example.com

# Pretty-print the JSON response
curl -s https://korpo.pro/api/v1/check/example.com | jq .

# Extract just the score
curl -s https://korpo.pro/api/v1/check/example.com \
  | jq '.score'

{
  "domain": "example.com",
  "score": 82,
  "spf": {\n    "found": true,\n    "record": "v=spf1 include:_spf.google.com -all",\n    "all_mechanism": "-all",\n    "issues": []
  },
  "dkim": {\n    "found": true,\n    "selectors_found": ["default"],\n    "issues": []
  },
  "dmarc": {\n    "found": true,\n    "record": "v=DMARC1; p=reject; rua=mailto:dmarc@example.com",\n    "policy": "reject",\n    "issues": []
  },
  "mtasts": {\n    "found": true,\n    "mode": "enforce",\n    "issues": []
  },
  "tlsrpt": {\n    "found": true,\n    "rua": ["mailto:tls-reports@example.com"],\n    "issues": []
  },
  "bimi": {\n    "found": false,\n    "issues": []
  },
  "issues": []
}

Email DeliverabilityChecker

Email Deliverability
Checker