Microsoft will retire Outlook Lite on May 25, 2026, after ceasing new installations in October 2025. Post-retirement, users can access the app, but mailbox access will be disabled. Microsoft encourages users to transition to Outlook Mobile, which is its primary mobile email experience. Outlook Lite was initially popular for its low resource requirements, achieving over 10 million downloads in 2024. The decision to retire it reflects a strategy to streamline offerings and adapt to evolving technology needs. No administrative action is required for organizations currently using Outlook Lite, aside from informing users about the changes.