MXToolbox Alternative — Free Email Deliverability API

Why Look for an MXToolbox Alternative?

MXToolbox is a popular email diagnostic tool, but it has limitations for developers and teams who need API access, automation, and integration capabilities.

mailcheck vs MXToolbox

Feature	mailcheck	MXToolbox
Free API Access	✓ 50 req/hr	✗ Paid only
REST API	✓ JSON responses	✗ GUI only (free)
Batch Checking	✓ Multiple domains	⚠ Limited
MTA-STS Check	✓	✗
BIMI Check	✓	✗
Open Source	✓ Self-hostable	✗
Crypto Payments	✓ BTC/LTC/XMR	✗
0–100 Score	✓ Quantified	⚠ Pass/Fail only

Try mailcheck Free

No signup needed. Just curl:

curl https://korpo.pro/api/v1/check/yourdomain.com

Check Your Domain →

Also try our free tools:

• Email Header Analyzer — Paste any email header, get SPF/DKIM/DMARC analysis
• MX Record Lookup — Find mail servers for any domain
• DNS Record Lookup — Check SPF, DKIM, DMARC records

See scores for popular domains: Gmail · Microsoft · ProtonMail