Introduction

Microsoft announced major changes coming in 2025 affecting the Microsoft 365 ecosystem, signaling the retirement of legacy features and tools crucial to IT administration and end-user productivity. This marks a significant milestone in Microsoft's plan to phase out older technologies and fully advance its modern productivity platforms, especially in sync with the end of support for Windows 10. IT administrators and organizations must prepare for these upcoming changes to safeguard their operations and optimize their Microsoft 365 experience.

Background and Context

Microsoft 365, the subscription-based productivity platform formerly known as Office 365, has evolved rapidly since its inception, integrating cloud-based solutions like Exchange Online, Microsoft Teams, SharePoint Online, and OneDrive. However, many older functionalities and support for legacy platforms remain in place, notably for Windows 10 and earlier Office versions such as Office 2016 and 2019.

As of October 14, 2025, Microsoft will officially end support for Microsoft 365 apps running on Windows 10, aligning with the end of Windows 10's own support lifecycle. Alongside this, several older Microsoft 365 features and tools, like legacy cmdlets in Exchange Online and the Remote Desktop app for Windows, will be retired or replaced with modern alternatives.

Key Changes and Retirements

1. Microsoft 365 Apps on Windows 10

  • End of Support Date: October 14, 2025
  • Post this date, Microsoft 365 apps such as Word, Excel, Outlook, and Teams will no longer receive updates, security patches, or technical support on Windows 10.
  • These apps will continue to function but may suffer from performance degradation and increased security vulnerabilities over time.
  • Microsoft strongly encourages upgrading to Windows 11, which offers enhanced security features including TPM 2.0 and a modernized user experience.

2. Legacy Exchange Online Cmdlets Retirement

  • Microsoft will retire cmdlets like INLINECODE0 and INLINECODE1 by March 2025.
  • The new INLINECODE2 cmdlet consolidates audit log searches across multiple Microsoft 365 services, including Exchange, Teams, SharePoint, and OneDrive.
  • This change simplifies audit management, enhances security monitoring and compliance reporting.

3. Remote Desktop Application Sunset

  • The classic Remote Desktop app for Windows will retire on May 27, 2025.
  • Microsoft will replace it with the newer Windows App, designed for easier access to Windows 365, Azure Virtual Desktop, and Microsoft Dev Box.

4. End of Support for Office 2016, 2019, and Exchange Server 2019

  • Support for these legacy Office suites and Exchange Server versions will end in October 2025.
  • Organizations must plan migrations to Microsoft 365 cloud services or newer on-premises offerings.

5. Removal of 'My Day' in Microsoft 365 Enterprise

  • The 'My Day' calendar and to-do feature will be retired by January 2025.
  • Microsoft Copilot AI assistant will replace it, offering more integrated and powerful productivity tools.

Implications for IT Administrators

  • Migration Planning: Enterprises must prepare for upgrading client OS to Windows 11 or planning for alternative support approaches.
  • Security Considerations: Unsupported apps expose organizations to vulnerabilities without security patches.
  • Compliance Risks: Continued use of unsupported software may fail regulatory requirements.
  • Training Needs: IT teams should familiarize themselves with new cmdlets, especially unified audit logging.
  • Infrastructure Modernization: Legacy Exchange environments face complex migrations to Exchange Server Subscription Edition or cloud alternatives.
  • User Communication: Clear messaging about impending changes and upgrade timelines is critical to reduce disruption.

Technical Details

  • Windows 11 hardware requirements (including TPM 2.0) restrict upgrades for many older devices, forcing hardware refresh strategies.
  • New unified audit logs support multi-service querying, improving efficiency and visibility in cloud environments.
  • Migration from legacy Exchange cmdlets requires script modifications and audit policy updates.
  • Microsoft 365 Copilot leverages AI-powered workflows replacing simpler tools like 'My Day'.

Conclusion

The changes scheduled for 2025 in Microsoft 365 and its supported platforms represent a decisive move toward modern, secure, and cloud-first productivity. IT administrators must proactively evaluate their environments, educate stakeholders, and execute migration plans to maintain security, compliance, and performance. While legacy support sunsets present challenges, they also open pathways for businesses to harness the latest innovations in Microsoft 365.