check before: 2025-06-01
Product:
Exchange, Microsoft 365 Apps, Microsoft 365 for the web, Outlook
Platform:
Online, US Instances, Web, World tenant
Status:
Change type:
Admin impact, Updated message, User impact
Links:
Details:
Summary:
Microsoft is changing how to enable or disable the new Outlook for Windows and Outlook for the web. The rollout will begin in late June 2025 and complete by mid-July 2025. The CASMailbox-`OWAEnabled` parameter will only affect Outlook for the web, while the new Outlook for Windows will be managed with the CASMailbox-`OneWinNativeOutlookEnabled` policy. No admin action is required before the rollout.
Details:
Updated May 8, 2025: We have updated the timeline below. Thank you for your patience.
We are changing how you enable or disable the new Microsoft Outlook for Windows and Microsoft Outlook for the web.
[When this will happen:]
General Availability (Worldwide, GCC): We will begin rolling out late June 2025 (previously late April) and expect to complete by mid-July 2025 (previously mid-May).
Change Category:
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Scope:
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Release Phase:
Created:
2024-11-01
updated:
2025-05-09
Task Type
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Docu to Check
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MS How does it affect me
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MS Preperations
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MS Urgency
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MS workload name
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summary for non-techies**
Microsoft is introducing separate settings for Outlook access, with CASMailbox-OWAEnabled controlling Outlook for the web and a new CASMailbox-OneWinNativeOutlookEnabled setting managing the new Outlook for Windows, effective automatically between late June and mid-July 2025.
Direct effects for Operations**
Change in Mailbox Access Control
The change in how mailbox access is controlled may lead to confusion among users regarding which version of Outlook they can access, potentially disrupting their workflow.
- roles: IT Admin, End User
- references: https://learn.microsoft.com/exchange/clients/outlook-on-the-web/mailbox-access, https://learn.microsoft.com/exchange/clients-and-mobile-in-exchange-online/outlook-on-the-web/enable-disable-employee-access-new-outlook
User Experience Disruption
Users may experience disruptions in their email access if they are not aware of the changes, leading to frustration and decreased productivity.
- roles: End User, Support Staff
- references: https://learn.microsoft.com/exchange/clients/outlook-on-the-web/mailbox-access, https://learn.microsoft.com/exchange/clients-and-mobile-in-exchange-online/outlook-on-the-web/enable-disable-employee-access-new-outlook
Increased Support Requests
The rollout may lead to an increase in support requests from users who are confused about the new settings and how to access their mailboxes.
- roles: Support Staff, IT Admin
- references: https://learn.microsoft.com/exchange/clients/outlook-on-the-web/mailbox-access, https://learn.microsoft.com/exchange/clients-and-mobile-in-exchange-online/outlook-on-the-web/enable-disable-employee-access-new-outlook
Documentation Updates Required
Organizations will need to update their internal documentation to reflect the new policies, which may lead to temporary inconsistencies in user guidance.
- roles: IT Admin, Documentation Specialist
- references: https://learn.microsoft.com/exchange/clients/outlook-on-the-web/mailbox-access, https://learn.microsoft.com/exchange/clients-and-mobile-in-exchange-online/outlook-on-the-web/enable-disable-employee-access-new-outlook
Potential for Misconfiguration
Without proper preparation, there is a risk of misconfiguration of the new settings, which could lead to users being unable to access their email.
- roles: IT Admin, End User
- references: https://learn.microsoft.com/exchange/clients/outlook-on-the-web/mailbox-access, https://learn.microsoft.com/exchange/clients-and-mobile-in-exchange-online/outlook-on-the-web/enable-disable-employee-access-new-outlook
Configutation Options**
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Opportunities**
Improved User Experience with New Outlook Features
The transition to the new Outlook for Windows and Outlook for the web presents an opportunity to enhance user experience through the adoption of modern features such as improved interface, enhanced performance, and better integration with other Microsoft 365 services. This can lead to increased productivity and user satisfaction.
- next-steps: Conduct user training sessions to familiarize employees with the new features of Outlook. Gather feedback to continuously improve the user experience and address any concerns.
- roles: End Users, IT Support, Training Coordinators
- references: https://learn.microsoft.com/exchange/clients/outlook-on-the-web/mailbox-access, https://learn.microsoft.com/exchange/clients-and-mobile-in-exchange-online/outlook-on-the-web/enable-disable-employee-access-new-outlook
Streamlined Administrative Management
The change in how Outlook is enabled/disabled allows for clearer management of user access to different Outlook versions. This can simplify administrative tasks and reduce the potential for configuration errors, as the settings are now more distinct and manageable.
- next-steps: Review current configurations and update documentation to reflect the new management policies. Train IT administrators on the new parameters to ensure proper implementation and management.
- roles: IT Administrators, System Managers, Compliance Officers
- references: https://learn.microsoft.com/exchange/clients/outlook-on-the-web/mailbox-access, https://learn.microsoft.com/exchange/clients-and-mobile-in-exchange-online/outlook-on-the-web/enable-disable-employee-access-new-outlook
Enhanced Compliance and Security Management
By allowing separate management of Outlook for Windows and Outlook for the web, organizations can enforce compliance and security policies more effectively. This ensures that sensitive information can be protected based on the platform being used, reducing risk.
- next-steps: Assess current compliance and security policies in relation to email access. Update these policies to leverage the new settings for better control and monitoring of user access.
- roles: Compliance Officers, Security Administrators, IT Managers
- references: https://learn.microsoft.com/exchange/clients/outlook-on-the-web/mailbox-access, https://learn.microsoft.com/exchange/clients-and-mobile-in-exchange-online/outlook-on-the-web/enable-disable-employee-access-new-outlook
Potentional Risks**
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IT Security**
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explanation for non-techies**
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change history
| Date | Property | old | new |
| 2025-05-09 | MC Last Updated | 03/27/2025 18:18:44 | 2025-05-08T22:47:51Z |
| 2025-05-09 | MC Messages | Updated March 27, 2025: We have updated the content. Thank you for your patience.
We are changing how you enable or disable the new Microsoft Outlook for Windows and Microsoft Outlook for the web. [When this will happen:] General Availability (Worldwide, GCC): We will begin rolling out late April 2025 (previously late February) and expect to complete by mid-May 2025 (previously mid-March). | Updated May 8, 2025: We have updated the timeline below. Thank you for your patience.
We are changing how you enable or disable the new Microsoft Outlook for Windows and Microsoft Outlook for the web. [When this will happen:] General Availability (Worldwide, GCC): We will begin rolling out late June 2025 (previously late April) and expect to complete by mid-July 2025 (previously mid-May). |
| 2025-05-09 | MC End Time | 06/30/2025 09:00:00 | 2025-08-25T09:00:00Z |
| 2025-05-09 | MC Summary | Microsoft is changing how to enable or disable the new Outlook for Windows and Outlook for the web. The rollout will start in late April 2025 and finish by mid-May 2025. The CASMailbox-`OWAEnabled` parameter will only block Outlook for the web, while the CASMailbox-`OneWinNativeOutlookEnabled` policy will manage the new Outlook for Windows. No admin action is required before the rollout. | Microsoft is changing how to enable or disable the new Outlook for Windows and Outlook for the web. The rollout will begin in late June 2025 and complete by mid-July 2025. The CASMailbox-`OWAEnabled` parameter will only affect Outlook for the web, while the new Outlook for Windows will be managed with the CASMailbox-`OneWinNativeOutlookEnabled` policy. No admin action is required before the rollout. |
| 2025-03-28 | MC Last Updated | 02/10/2025 22:15:48 | 2025-03-27T18:18:44Z |
| 2025-03-28 | MC Messages | Updated February 10, 2025: We have updated the content. Thank you for your patience.
We are changing how you enable or disable the new Microsoft Outlook for Windows and Microsoft Outlook for the web. [When this will happen:] General Availability (Worldwide, GCC): We will begin rolling out late February 2025 (previously late January) and expect to complete by mid-March 2025 (previously mid-February). | Updated March 27, 2025: We have updated the content. Thank you for your patience.
We are changing how you enable or disable the new Microsoft Outlook for Windows and Microsoft Outlook for the web. [When this will happen:] General Availability (Worldwide, GCC): We will begin rolling out late April 2025 (previously late February) and expect to complete by mid-May 2025 (previously mid-March). |
| 2025-03-28 | MC End Time | 04/28/2025 09:00:00 | 2025-06-30T09:00:00Z |
| 2025-03-28 | MC Summary | Microsoft is updating the process to enable/disable new Outlook for Windows and Outlook for the web, starting late January 2025. The rollout will change the CASMailbox parameters, separating the controls for web and Windows versions. Organizations should review configurations and update documentation accordingly. No admin action is required before the rollout. | Microsoft is changing how to enable or disable the new Outlook for Windows and Outlook for the web. The rollout will start in late April 2025 and finish by mid-May 2025. The CASMailbox-`OWAEnabled` parameter will only block Outlook for the web, while the CASMailbox-`OneWinNativeOutlookEnabled` policy will manage the new Outlook for Windows. No admin action is required before the rollout. |
| 2025-02-11 | MC Messages | Updated January 29, 2025: We have updated the rollout timeline below. Thank you for your patience.
We are changing how you enable or disable the new Microsoft Outlook for Windows and Microsoft Outlook for the web. [When this will happen:] General Availability (Worldwide, GCC): We will begin rolling out late February 2025 (previously late January) and expect to complete by mid-March 2025 (previously mid-February). | Updated February 10, 2025: We have updated the content. Thank you for your patience.
We are changing how you enable or disable the new Microsoft Outlook for Windows and Microsoft Outlook for the web. [When this will happen:] General Availability (Worldwide, GCC): We will begin rolling out late February 2025 (previously late January) and expect to complete by mid-March 2025 (previously mid-February). |
| 2025-02-11 | MC How Affect | We're changing the CASMailbox -OWAEnabled parameter that enables or disables access to user mailboxes using Outlook for the web (formerly known as Outlook Web App or OWA) to block only Outlook for the web and to not affect the behavior of new Outlook for Windows.
You can manage new Outlook for Windows with the CASMailbox-OneWinNativeOutlookEnabled policy. You are receiving this message because our reporting indicates one or more users in your organization may be using the New Outlook for Windows. Note: We will not change any existing value for the settings, but we will change which setting is checked to see if new Outlook for Windows is allowed to run on that computer. Before this rollout, both CASMailbox-OWAEnabled and CASMailboxOneWinNativeOutlookEnabled policies are checked. After this rollout, we will remove the check for CASMailbox-OWAEnabled so you can have the chance to enable new Outlook and still disable Outlook for the web if desired. | We're changing the CASMailbox -OWAEnabled parameter that enables or disables access to user mailboxes using Outlook for the web (formerly known as Outlook Web App or OWA) to block only Outlook for the web and to not affect the behavior of new Outlook for Windows.
You can manage new Outlook for Windows with the CASMailbox-OneWinNativeOutlookEnabled policy. You are receiving this message because our reporting indicates one or more users in your organization may be using the New Outlook for Windows. Note: We will not change any existing value for the settings, but we will change which setting controls if the new Outlook for Windows is allowed for the user. Before this rollout, both CASMailbox-OWAEnabled and CASMailboxOneWinNativeOutlookEnabled policies are checked. After this rollout, we will remove the check for CASMailbox-OWAEnabled so you can have the chance to enable new Outlook and still disable Outlook for the web if desired. |
| 2025-02-11 | MC Last Updated | 01/29/2025 21:20:17 | 2025-02-10T22:15:48Z |
| 2025-01-30 | MC Last Updated | 11/06/2024 00:18:12 | 2025-01-29T21:20:17Z |
| 2025-01-30 | MC Messages | Updated November 5, 2024: We have updated the content. Thank you for your patience.
We are changing how you enable or disable the new Microsoft Outlook for Windows and Microsoft Outlook for the web. [When this will happen:] General Availability (Worldwide, GCC): We will begin rolling out late January 2025 and expect to complete by mid-February 2025. | Updated January 29, 2025: We have updated the rollout timeline below. Thank you for your patience.
We are changing how you enable or disable the new Microsoft Outlook for Windows and Microsoft Outlook for the web. [When this will happen:] General Availability (Worldwide, GCC): We will begin rolling out late February 2025 (previously late January) and expect to complete by mid-March 2025 (previously mid-February). |
| 2025-01-30 | MC End Time | 04/18/2025 09:00:00 | 2025-04-28T09:00:00Z |
| 2024-11-06 | MC prepare | This rollout will happen automatically by the specified date with no admin action required before the rollout. Review your current configuration to determine the impact for your organization. You may want to notify your admins about this change and update any relevant documentation.
After this change takes effect, please confirm the OneWinNativeOutlookEnabled policy state for each mailbox. The default value is Enabled. Learn more Enable or disable Outlook on the web access to mailboxes in Exchange Server | Microsoft Learn (will be updated before rollout) Enable or disable access to the new Outlook for Windows | Microsoft Learn (will be updated before rollout) #newoutlookforwindows https://learn.microsoft.com/exchange/clients/outlook-on-the-web/mailbox-access https://learn.microsoft.com/exchange/clients-and-mobile-in-exchange-online/outlook-on-the-web/enable-disable-employee-access-new-outlook | This rollout will happen automatically by the specified date with no admin action required before the rollout. Review your current configuration to determine the impact for your organization. You may want to notify your admins about this change and update any relevant documentation.
After this change takes effect, please confirm the CASMailbox OneWinNativeOutlookEnabled policy state for each mailbox. The default value is Enabled. Learn more Enable or disable Outlook on the web access to mailboxes in Exchange Server | Microsoft Learn (will be updated before rollout) Enable or disable access to the new Outlook for Windows | Microsoft Learn (will be updated before rollout) #newoutlookforwindows https://learn.microsoft.com/exchange/clients/outlook-on-the-web/mailbox-access https://learn.microsoft.com/exchange/clients-and-mobile-in-exchange-online/outlook-on-the-web/enable-disable-employee-access-new-outlook |
| 2024-11-06 | MC MessageTagNames | User impact, Admin impact | Updated message, User impact, Admin impact |
| 2024-11-06 | MC Summary | Microsoft is updating the process to enable/disable Outlook for Windows and Outlook for the web, with changes rolling out from late January to mid-February 2025. The OWAEnabled parameter will only affect Outlook for the web, while the OneWinNativeOutlookEnabled policy will manage new Outlook for Windows. No admin action is required before the rollout. | Microsoft is updating the process to enable/disable new Outlook for Windows and Outlook for the web, starting late January 2025. The rollout will change the CASMailbox parameters, separating the controls for web and Windows versions. Organizations should review configurations and update documentation accordingly. No admin action is required before the rollout. |
| 2024-11-06 | MC Last Updated | 11/01/2024 00:03:57 | 2024-11-06T00:18:12Z |
| 2024-11-06 | MC Messages | We are changing how you enable or disable the new Microsoft Outlook for Windows and Microsoft Outlook for the web.
[When this will happen:] General Availability (Worldwide, GCC): We will begin rolling out late January 2025 and expect to complete by mid-February 2025. | Updated November 5, 2024: We have updated the content. Thank you for your patience.
We are changing how you enable or disable the new Microsoft Outlook for Windows and Microsoft Outlook for the web. [When this will happen:] General Availability (Worldwide, GCC): We will begin rolling out late January 2025 and expect to complete by mid-February 2025. |
| 2024-11-06 | MC Title | Microsoft new Outlook for Windows and Outlook for the web: Changing how to disable/enable | (Updated) Microsoft new Outlook for Windows and Outlook for the web: Changing how to disable/enable |
| 2024-11-06 | MC How Affect | We're changing the OWAEnabled parameter that enables or disables access to user mailboxes using Outlook for the web (formerly known as Outlook Web App or OWA) to block only Outlook for the web and to not affect the behavior of new Outlook for Windows.
You can manage new Outlook for Windows with the OneWinNativeOutlookEnabled policy. You are receiving this message because our reporting indicates one or more users in your organization may be using the New Outlook for Windows. Note: We will not change any existing value for the settings, but we will change which setting is checked to see if new Outlook for Windows is allowed to run on that computer. Before this rollout, both OWAEnabled and OneWinNativeOutlookEnabled policies are checked. After this rollout, we will remove the check for OWAEnabled so you can have the chance to enable new Outlook and still disable Outlook for the web if desired. | We're changing the CASMailbox -OWAEnabled parameter that enables or disables access to user mailboxes using Outlook for the web (formerly known as Outlook Web App or OWA) to block only Outlook for the web and to not affect the behavior of new Outlook for Windows.
You can manage new Outlook for Windows with the CASMailbox-OneWinNativeOutlookEnabled policy. You are receiving this message because our reporting indicates one or more users in your organization may be using the New Outlook for Windows. Note: We will not change any existing value for the settings, but we will change which setting is checked to see if new Outlook for Windows is allowed to run on that computer. Before this rollout, both CASMailbox-OWAEnabled and CASMailboxOneWinNativeOutlookEnabled policies are checked. After this rollout, we will remove the check for CASMailbox-OWAEnabled so you can have the chance to enable new Outlook and still disable Outlook for the web if desired. |
Last updated 1 month ago
