Microsoft new Outlook for Windows and Outlook for the web: Changing how to disable/enable

• https://learn.microsoft.com/microsoft-365-apps/outlook/manage/enable-new-outlook-if-outlook-web-is-blocked?view=o365-worldwidehttps%3A%2F%2Flearn.microsoft.com%2Fen-us%2Fmicrosoft-365-apps%2Foutlook%2Fmanage%2Fenable-new-outlook-if-outlook-web-is-blocked%3Fview%3Do365-worldwide
• https://entra.microsoft.com/#view/Microsoft_AAD_ConditionalAccess/ConditionalAccessBlade/~/Policies
• 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

1. 28 Jul 2025

   Updated May 8,July 28, 2025: We have updated the timeline below. Thank you for your patience. content, timeline, and additional resources. We are changing how you enable or disable the new Microsoft Outlook recommended method for Windows and Microsoft disabling 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 web so that users can continue to complete by mid-July 2025 (previously mid-May). Howaccess the new Outlook for Windows. When this will affect your organization: We're changing the CASMailbox -OWAEnabled parameter happen: There is no change that enables or disables access to user mailboxes using Outlook for the web (formerly known as Outlook Web App or OWA) is rolling out. We have published a new support article with instructions on how to use our existing infrastructure to block onlyusers from access Outlook for the web and to not affect the behavior of new without impacting Outlook for Windows. You can manage new Outlook for Windows with the CASMailbox-OneWinNativeOutlookEnabled policy. You are receiving How this message because our reporting indicates one or more userswill affect your organization: Admins can follow the instructions in your organization may be using the Newthis support article to block access to Outlook for Windows. Note: We will not change any existing value the web using Conditional Access. Blocking Outlook for the settings, but we will change which setting controls if the new web using this policy has no impact on Outlook for Windows is allowedWindows. Once Outlook 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 disableweb is blocked, admins can set the CASMailbox policy -OWAEnabled to $true. This will have no impact on users' ability to access outlook for the web since the work was already done to block Outlook for the web if desired. with another policy.  What you need to do to prepare: This rollout will happen automatically by the specified date with There are no admin action required before the rollout. Review your current configurationchanges to existing polices, so there is nothing you need to determine the impact for your organization. You may want do 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. prepare. 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

2. 8 May 2025

   Updated March 27,May 8, 2025: We have updated the content.timeline below. Thank you for your patience. We are changing how you enable or … will happen: General Availability (Worldwide, GCC): We will begin rolling out late AprilJune 2025 (previously late February)April) and expect to complete by mid-Maymid-July 2025 (previously mid-March).mid-May). How this will affect your organization: We're changing the CASMailbox -OWAEnabled parameter …

3. 27 Mar 2025

   Updated February 10,March 27, 2025: We have updated the content. Thank you for your patience. We … will happen: General Availability (Worldwide, GCC): We will begin rolling out late FebruaryApril 2025 (previously late January)February) and expect to complete by mid-Marchmid-May 2025 (previously mid-February).mid-March). How this will affect your organization: We're changing the CASMailbox -OWAEnabled parameter …

4. 10 Feb 2025

   Updated January 29,February 10, 2025: We have updated the rollout timeline below. content. Thank you for your patience. We are changing how you enable or … any existing value for the settings, but we will change which setting is checked to see if controls if the new Outlook for Windows is allowed to run on that computer.for the user. Before this rollout, both CASMailbox-OWAEnabled and CASMailboxOneWinNativeOutlookEnabled policies are checked. After this …

5. 29 Jan 2025

   … will happen: General Availability (Worldwide, GCC): We will begin rolling out late JanuaryFebruary 2025 (previously late January) and expect to complete by mid-March 2025 (previously mid-February). How this will …

6. 29 Jan 2025

   Updated November 5, 2024:January 29, 2025: We have updated the content.rollout timeline below. Thank you for your patience. We are changing how you enable or … will begin rolling out late January 2025 and expect to complete by mid-February 2025.mid-March 2025 (previously mid-February). How this will affect your organization: We're changing the CASMailbox -OWAEnabled parameter …

7. 5 Nov 2024
   • Tags User impact, Admin impact → Updated message, User impact, Admin impact

   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 … by mid-February 2025. How this will affect your organization: We're changing the OWAEnabledCASMailbox -OWAEnabled parameter that enables or disables access to user mailboxes using Outlook for … Outlook for Windows. You can manage new Outlook for Windows with the OneWinNativeOutlookEnabledCASMailbox-OneWinNativeOutlookEnabled policy. You are receiving this message because our reporting indicates one or … Windows is allowed to run on that computer. Before this rollout, both OWAEnabledCASMailbox-OWAEnabled and OneWinNativeOutlookEnabledCASMailboxOneWinNativeOutlookEnabled policies are checked. After this rollout, we will remove the check for OWAEnabledCASMailbox-OWAEnabled so you can have the chance to enable new Outlook and still … 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 …

8. 31 Oct 2024 · first version seen

The notice links to no Microsoft Learn or Support page that this installation reads.

No related evidence found in this installation's recent collection. This does not establish that no announcement exists.

• Whether your tenant is affected: this is Microsoft's notice, not a check of your settings.