💡 Our Technical Review in summary
Summary
- Microsoft has announced a significant delay to the “opt-out” phase for the new Outlook for Windows in Enterprise environments.
- The start date for this transition has been moved from April 2026 to March 2027, providing organizations with an additional 11 months of preparation time.
- This extension is intended to allow Microsoft to continue delivering requested features and improvements while ensuring organizations can align the migration with their own readiness timelines.
Impact
- Timeline Extension: Organizations now have until March 2027 before the opt-out phase begins, where users might be automatically toggled to the new experience with the option to switch back.
- Admin Control: Existing policies used to hide the “New Outlook” toggle or disable the application remain fully effective. Users will not be migrated if the toggle is hidden via policy or if the “Policy of automatic migration” is set to opt-out.
- Exemptions: The migration does not currently apply to users on perpetual licenses (e.g., Office 2021) or those using on-premise accounts.
- User Experience: When the opt-out phase eventually begins, migrated users will see onboarding prompts but retain the ability to revert to classic Outlook during the transition period.
- Government Clouds: Timelines for GCC High and DoD environments are not included in this update and will be communicated at a later date.
Action Required
- Update Rollout Plans: Adjust your internal IT roadmap to reflect the new March 2027 deadline for the opt-out phase.
- Utilize Admin-Controlled Migration: Use the “Admin-controlled migration” policy to move specific groups (such as Copilot users or early adopters) to the new Outlook in a staged, reversible manner.
- Assess Readiness: Continue evaluating web add-in compatibility and feature parity between classic and new Outlook to identify potential gaps for your workflow.
- Pilot Programs: Conduct pilot tests with small groups using Entra ID group targeting to gather feedback and refine configuration settings.
- Enable the Toggle: If you previously disabled the toggle globally, consider re-enabling it for specific test groups to encourage voluntary adoption before the mandatory phases begin.
- Review Resources: Leverage the Microsoft Adoption Kit for communication templates, checklists, and project planning tools.
Microsoft Official Update
Service: N/A
Category: planForChange
Severity: normal
Updated February 20, 2026: We have updated the timeline. Thank you for your patience.
[Introduction]
Microsoft is updating the opt‑out phase start date for new Outlook for Windows in Enterprise environments from April 2026 to March 2027.
[When this will happen:]
- The opt‑out phase for Enterprise environments will now begin in March 2027 (previously April 2026), providing organizations with 12 months of lead time to prepare.
- GCC High and DoD timelines will be communicated separately at a later date.
Why is there a change to the timeline?
We’re seeing strong and accelerating adoption of new Outlook as organizations progress on timelines that match their readiness. At the same time, we continue to invest heavily in expanding capabilities and addressing feedback from customers who want to go further with new Outlook. To ensure organizations have the time they need to prepare—and to fully realize the value of ongoing innovation—we’re extending the opt-out timeline and providing 12 months of lead time as we continue delivering key features and improvements.
[How this affects your organization:]
Who is affected:
- Microsoft 365 administrators managing Outlook for Windows.
- Users of classic Outlook for Windows.
- Organizations that previously disabled the new Outlook toggle or have not yet begun migration planning.
What will happen:
- Migrated users will receive in‑app onboarding prompts and can switch back to classic Outlook if needed.
- Existing policies that disable or limit access to new Outlook will remain in effect.
- Admins can continue using Admin‑controlled migration to move users in a staged, reversible manner ahead of time.
- Users will not be migrated if one or more of the following is true:
- You have opted out users using the Policy of automatic migration
- New Outlook toggle is hidden via policy
- Perpetual license is in use
- On premise account
[What you can do to prepare:]
Prepare your organization for the opt-out phase that will begin March 2027. Evaluate and use the Admin-controlled migration policy to the stage and schedule that is right for your organization.
Take preparatory steps to:
- Assess feature and web add-in readiness.
- Conduct any needed pilots.
- Build a timeline that works for your organization.
- Re-enable the toggle if previously disabled and enable the Admin-controlled migration policy to move forward.
Be sure to communicate with your users about what to expect, and leverage Microsoft’s adoption resources to make the experience smooth.
Resources and Support:
Microsoft is committed to helping you manage this transition effectively. Refer to the following resources for detailed guidance and tools:
- Adoption Kit: A downloadable kit with checklists, project planning templates, user communication examples, and FAQs to support your rollout. New Microsoft Outlook for Windows – Microsoft Adoption.
- Tips for new users: Start new users in new Outlook | Microsoft Learn.
- Control installation and use: If you have previously disabled the new Outlook toggle via policy and now want to roll out new Outlook. Control installation and use of new Outlook | Microsoft Learn.
- Policy for Admin-controlled migration: This policy allows you to toggle users into new Outlook in a controlled manner, with in-app prompts that ease users into the new experience over successive Outlook launches. Users who are moved by policy will be presented with a user-friendly onboarding experience and will have the option to switch back to classic Outlook. Microsoft recommends starting with new users in your organizations and those piloting and using Copilot as early target audiences. Policy for Admin-Controlled Migration to new Outlook for Windows | Microsoft Learn; User-facing article.
[Compliance considerations]
| Question | Explanation |
|---|---|
| Does the change include an admin control? | Admins can manage the change using the policy for automatic migration and existing Outlook policies. |
| Can the change be controlled through Entra ID group membership? | Migration can be scoped to specific users or groups using Entra ID group targeting. |
| Does the change allow a user to enable and disable the feature themselves? | Users moved to new Outlook can switch back to classic Outlook during the transition period. |
