When a service is breached, the stolen data ends up in databases circulating among attackers. If your domain appears in those databases, accounts using your domain's email addresses have been compromised.
What domain breach exposure means
When a breach database contains [email protected], it typically means:
- Someone used a
@yourdomain.comemail to sign up for a third-party service that was later breached, or - Your own systems were breached and customer or employee data was stolen
The first scenario is far more common — but it still matters, because those users may be reusing passwords on your site.
Why it matters for your site
- Credential stuffing — attackers try breached username/password pairs on other sites. If your users reuse passwords, their accounts are at risk.
- Targeted phishing — breach data enables personalised attacks against your users.
- Reputation damage — if your own systems were the source, the trust impact is significant.
How to check
Services like Have I Been Pwned (haveibeenpwned.com) let you search by domain to see which email addresses from your domain have appeared in known breaches.
threatprobe.app's free scan includes a domain breach exposure count. The Basic report adds a personal email check (provided at checkout). Full extends this to 9 addresses — your email plus common role accounts (admin@, info@, support@, and others).