Email security risks come in many forms, from phishing attacks to malware, and each requires a different approach to mitigate the risk.
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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.
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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.