Microsoft is working on including a new Office 365 Advanced Threat Protection (ATP) feature that would block email sender domains automatically if they fail DMARC authentication. Microsoft is also planning to block malicious content in Office 365 regardless of the custom configurations unless manually overridden by admins or users. Microsoft also warned Office 365 admins and users against bypassing the built-in spam filters in June 2019, in a support document that also shares guidelines for cases when this can’t be avoided. The feature is planned to roll out to all environments together with another one designed to also boost the default security of email inboxes protected by Office 365 ATP.
Source: https://www.bleepingcomputer.com/news/security/office-365-atp-to-block-email-domains-that-fail-authentication/