If enabled, any person with a free Microsoft account (Teams Personal) can DM and call your users. This is a primary Teams phishing vector — attackers spoof internal user display names and message employees with credential-harvesting links.
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 Sharing & Collaboration checks
Check your own tenant
Is your tenant covered on "block personal teams accounts"?
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.