Free tools

Free email tools

Utilities from the Email SDK project — free, no signup, built on the same data and checks the SDK uses.

Email DNS checker

Check a domain's SPF, DKIM, DMARC, and MX records with pass/warn/fail explanations and provider-specific setup links.

Side-by-side message-field support for Resend, Postmark, SendGrid, Mailgun, AWS SES, Brevo, and more — from the SDK's own capability matrix.