IT Club
IT Club Domain Security Checker

Check your business email security

Check the public DNS records that help authenticate business email. Results are a point-in-time view, not a security verdict.

Public records onlyRuns in your browser

Free tool

Check a domain

Check DKIM selectors (optional)
up to 5

Separate selectors with commas, spaces or new lines.

Need help finding a selector?

Your provider's setup page shows the selector in the DNS record name. During a mail migration, both the old and new selectors can be active.

Microsoft 365For domains managed in Exchange Online.Open DKIM settings for your domain and use the label before ._domainkey in the CNAME names, usually selector1 or selector2.Google WorkspaceFor Gmail on a business domain.Open Authenticate email for your domain. Google shows the selector used in the DNS name, before ._domainkey.Zoho MailFor domains sending through Zoho Mail.Open DKIM configuration for your domain and copy the selector shown for the key you want to check.FastmailFor custom domains hosted with Fastmail.Open your domain's DNS settings and use the label before ._domainkey in the DKIM record name.

Only public DNS records are checked. No account, password or mailbox access is needed.

What we look for

Four public record types.

SPF

Which services are allowed to send as your domain.

DKIM

A cryptographic signature, if you provide its selector.

DMARC

The instruction receivers follow when something does not match.

MX + DNSSEC

Where mail goes, and whether DNS answers can be trusted.

Private by design

This checker sends only the domain and optional DKIM selectors to a public DNS-over-HTTPS resolver. It does not ask for passwords, mailbox logins, API keys or private credentials. Nothing is saved by this page.

A useful first look, not a certificate

DNS records can be incomplete, cached or specific to your mail provider. This page cannot test message delivery, mailbox configuration or selectors you did not provide. If a result is unclear, ask your provider for the exact record to publish.

Next, make sense of the settings

A DMARC record is only helpful when you know what to do with it.

Our small-business checklist explains the policy choices in plain English, including how to move from monitoring to stronger protection without guessing.

Read the DMARC small-business checklist

Good security starts with knowing what is already public.