Email security risks come in many forms, from phishing attacks to malware, and each requires a different approach to mitigate the risk.
Surviving the Shark-Infested Waters of Mail Security Risks
There is no single magic solution to protect your organization against the various mail threats that were described earlier in this post.
Automatically disable AD users using Microsoft Defender for Identity
Leverage Microsoft Defender for Identity to stop advanced on-premises Active Directory threats using M365 Defender custom detection rules.