Progressive stages of migration to new Outlook for Windows

Overview

This article provides a detailed timeline and roadmap for migrating to new Outlook for Windows, and outlines the three progressive stages of migration: opt in, opt out, and cutover. The information is designed to help administrators prepare for the migration to new Outlook by understanding expected communications and the necessary preparations for each stage.

Progressive stages of migration

Stage 1: Opt-in

Currently, new Outlook for Windows is in the opt-in stage. Customers see the Try the new Outlook toggle at the top right of the classic Outlook experience. New Outlook is off by default, and users can toggle to try the new experience. If certain features or workflows aren't yet available, users can switch back to classic Outlook. Both versions can run side-by-side, allowing users to compare their experiences. Feedback collected during this stage helps drive feature development and readiness for the next stage.

To run both classic and new Outlook side-by-side, see Run new Outlook and classic Outlook side-by-side.

Milestone: General Availability (GA)

By August 1, 2024, new Outlook for Windows will move out of preview and into General Availability (GA). Customers with relevant licensing can obtain regular and assisted technical support through their respective Microsoft support programs. Feature development will continue, and feedback will guide prioritization of further releases.

For more information about support and feedback, see the article: Contact support and provide feedback in the new Outlook for Windows.

Stage 2: Opt-out

After a period for feature capability development and quality assessment, the migration will move to the opt-out stage. In this stage, new Outlook is on by default, automatically bringing users into the new experience. IT administrators will have at least 12 months notice before this stage is implemented in managed Enterprise plans. Users can still revert to classic Outlook during this stage if needed.

For more resources to assist with adoption and migration, see New Outlook for Windows Adoption.

Stage 3: Cutover

In the cutover stage, users are no longer be able to switch back to classic Outlook. New deployments of Outlook with Microsoft 365 subscriptions will feature new Outlook for Windows. IT administrators will have at least 12 months' notice before the cutover stage is implemented in Production rings. Existing installations of classic Outlook through perpetual licensing will continue to be supported until at least 2029.

Communication between stages

The journey through these stages is represented in the timeline shown. After General Availability, Microsoft will use existing channels to provide a "notice of disruptive change" 12-months before moving to the opt-out and cutover stages in production rings.

Prepare for migration and deployment

To prepare your organization for migration, consider the following steps:

1. Reach out to stakeholders. These include end-users, power users, and teams with specific capability requirements. Conduct a thorough evaluation of the new Outlook experience.
2. Define the scope of testing and review. Assess the effect of new Outlook for Windows on your existing workflows. Information on released and upcoming features can be found in the new Outlook for Windows roadmap.
3. Begin readiness planning. Regardless of the size of your team, readiness planning is critical to ensure your organization is ready for new Outlook for Windows. Utilize resources for learning, migration, and user communications are available in the new Outlook for Windows migration kit.