Postscale Check · free
Email authentication check
Check the DNS records that receivers use to decide whether mail from a domain is legitimate: MX, SPF, DKIM, DMARC, MTA-STS and TLS-RPT.
What this checks
This runs the same setup checklist we use during Postscale domain onboarding: whether the domain can receive mail, which senders SPF authorizes, whether DKIM is published for a selector, whether DMARC has enforcement, and whether SMTP TLS reporting is configured.
DKIM selectors are not discoverable from DNS alone. Enter a selector from a DKIM-Signature header for a definitive check; otherwise the tool tests common selectors and reports that result separately.
Need this in production?
The free tool is great for one-off checks. For automated monitoring, alerting, and an API, see the related Postscale product.
See the Transactional Email API