Free & Open Source

Email Deliverability
Checker

Check SPF, DKIM, DMARC for any domain — free, instant, no signup

Press Enter or click Check — rate limited to 50 requests/hour

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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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Features

Everything you need to
verify email auth

A comprehensive, developer-friendly toolkit for auditing email deliverability — from DNS records to compliance.

🛡️

SPF Analysis

Validates your Sender Policy Framework records, checks for common misconfigurations like missing all mechanisms and DNS lookup limits.

🔐

DKIM Verification

Scans for DKIM public keys across common selectors and validates key strength, ensuring your emails carry a cryptographic seal.

📋

DMARC Audit

Checks your DMARC policy enforcement level, reporting endpoints, and subdomain handling — helping you move from monitoring to reject.

⚡

Instant Results

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

🔗

REST API

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

📖

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": {
    "found": true,
    "record": "v=spf1 include:_spf.google.com -all",
    "all_mechanism": "-all",
    "issues": []
  },
  "dkim": {
    "found": true,
    "selectors_found": ["default"],
    "issues": []
  },
  "dmarc": {
    "found": true,
    "record": "v=DMARC1; p=reject; rua=mailto:dmarc@example.com",
    "policy": "reject",
    "issues": []
  },
  "issues": []
}

Email DeliverabilityChecker

Email Deliverability
Checker