abuse.ch publishes blocklists of hostnames serving malware (URLhaus) and botnet command-and-control IPs (Feodo Tracker). If one of your own assets is listed, it has been compromised and is being used against others — and it will also get your mail and traffic blocked.
A scan reports where your tenant stands on this check — pass, fail with a step-by-step fix, or not applicable if your licensing doesn’t include the feature. When Tenant Strike can’t read a setting with read-only access, it says unverified and gives you a one-command way to confirm it yourself — it never guesses.
Related External Attack Surface checks
Check your own tenant
Is your tenant covered on "stay off threat blocklists"?
One read-only scan answers it — this check and every other one in the catalog, each with a plain-English fix. 7-day Pro trial, no credit card.