Microsoft Defender for Office 365 is an email and collaboration security solution designed to protect Microsoft 365 environments from email-based threats and attacks targeting collaboration tools. The product provides protection against phishing attacks, including those using malicious links and QR codes, business email compromise (BEC), and malware. The solution extends protection beyond email to cover Microsoft Teams, SharePoint, and OneDrive with inline protection against malicious URLs and real-time detonation of attachments and links. It uses AI-powered sentiment analysis and large language models to detect attacker intent and filter malicious content. The platform includes extended detection and response (XDR) capabilities that analyze attacker intent, identify compromised assets, and contain threats in near-real time. Automated response features enable automatic disabling of compromised users, isolation of compromised devices, and post-delivery removal of malicious emails. Security teams receive visibility into threats through alerts and data across Microsoft collaboration tools, with investigation and hunting capabilities through a unified incident experience. The solution provides security posture optimization through recommended configurations and offers priority account support for sensitive accounts. The product includes security awareness training capabilities with phishing simulations and targeted education. Available in two plans (Plan 1 and Plan 2), it is also included in Microsoft Defender Suite.