All news with #defender for office 365 tag

Microsoft named Leader in 2025 Gartner Email Security

🔒 Microsoft has been named a Leader in the 2025 Gartner® Magic Quadrant for Email Security, recognizing advances in Microsoft Defender for Office 365. The announcement highlights agentic AI innovations and automated workflows—including an agentic email grading system and the Microsoft Security Copilot Phishing Triage Agent—that reduce manual triage and speed investigations. Microsoft also cites new protections like email bombing detection and expanded coverage across collaboration surfaces such as Microsoft Teams, while committing to greater transparency through in-product benchmarking and reporting.

Microsoft Teams guest chat exposes cross-tenant blind spot

🔒 Security researchers warn that a cross-tenant collaboration design in Microsoft Teams can cause a user's Defender for Office 365 protections to be dropped when they accept a guest invitation and join another tenant. The default-enabled feature MC1182004 (chat with any email) lowers the bar for attackers to spin up hostile tenants and deliver links or files that bypass URL scanning, Safe Links, file sandboxing and zero-hour auto purge. Administrators are advised to treat guest access as a trust boundary: restrict B2B invites to vetted domains, enforce Entra ID cross-tenant policies, and disable the 'chat with Anyone' capability where appropriate.

Microsoft Enables Default Auto-Archiving in Exchange Online

📥 Microsoft is enabling threshold-based auto-archiving by default for Exchange Online, moving the oldest items to users' archive mailboxes when primary mailbox usage approaches 90%, provided an archive is provisioned and has available space. The Managed Folder Assistant will continuously monitor mailbox sizes and archive until usage drops below the threshold. Rollout begins this month for public clouds and is scheduled for government clouds in November; users can tag items with the Never Move to Archive flag to prevent them from being archived. The change complements recent Defender for Office 365 updates that detect email bombing attacks.