Microsoft wants to add a new Office 365 feature to allow customers to test Microsoft Defender email protection without actually having to configure the environment and devices for your organization. Microsoft Defender for Office 365 Advanced Threat Protection provides Office 365 enterprise accounts with email protection from several threats including credential phishing and business email compromise, as well as automated remediation of detected attacks. The feature will soon be available in public preview, with Microsoft planning to make it generally available to all customers in standard multi-tenants with compatible licenses.
Source: https://www.bleepingcomputer.com/news/security/microsoft-defender-for-office-365-to-allow-testing-without-setup/