March 11, 2026
BlogMicrosoft Delays By a Year Its New Outlook Rollout
In late Feb. 2026, Microsoft added a notice in the Microsoft 365 Admin Center (MC949965) about a delay in the rollout of its New Outlook for Windows.
“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.”
(Microsoft’s update noted that the GCC High and DoD rollout timelines will be provided at some later date.
Microsoft’s update claimed the company is seeing “strong and accelerating adoption of new Outlook.” But it added that Microsoft is pushing to expand capabilities and address “feedback from customers who want to go further with the new Outlook.”
The Long, Slow March to New Outlook
Microsoft has told customers to expect a handful of milestones as it moves to replace the current Outlook with the new Outlook. Microsoft had designated the New Outlook as “Opt-in” and off by default in Mar. 2024. Microsoft declared New Outlook to be generally available shortly thereafter, on Aug. 1, 2024.
New Outlook was scheduled to hit the “Opt-out”/on-by-default milestone in April 2026. But now Opt-out isn’t slated until March 2027. After opt-out, managed customers will receive a minimum of 12-month notice before the “Cutover” stage begins — now, no earlier than March 2028. After Cutover, customers won’t be able to switch back to Classic Outlook, and new deployments of Outlook with Microsoft 365 subscriptions will come with the New Outlook.
However, in 2024, Microsoft admitted that existing classic Outlook installations — both perpetual and subscription — will continue to be supported until at least 2029. After Directions on Microsoft asked, Microsoft said that existing enterprise customers with a Microsoft 365 subscription or license that includes desktop apps will be able to download classic Outlook separately and use for no additional fee.
New Outlook has missing features and annoyances, the same as any Office app in beta testing. The trouble is, it’s not in beta testing. It’s generally available and it was about to land on the desktop of every Microsoft 365 Apps for enterprise user, unless their enterprise opted out.
Many will opt out, some until 2029, the earliest date that classic Outlook could be retired. These companies now have 11 more months to adjust their Office deployment and updating processes to keep New Outlook out.
And If You Don’t Want to Delay…
What about companies that want New Outlook? There will be some, although they might not know it yet. Outlook already uses machine learning and other AI methods for things like spam filtering and scheduling. Generative AI is accelerating improvements, and the improvements will mostly come to New Outlook, not Classic.
Companies that see payoff from AI in apps like Outlook can’t cling to Classic for long. For these companies, the delay means more time to clear away migration blockers, like classic Outlook extensions that don’t work on New Outlook.
There’s also possibly the biggest migration blocker of all: Exchange on-premises or in third-party hosting . New Outlook treats these Exchange systems like any other Internet mail service, with no more calendar integration or other features than you would get with Yahoo or Google. That means companies that want the coming AI capabilities of New Outlook will have to move to Exchange Online. Unless, of course, Microsoft changes its plans.
For more details on the evolution of e-mail and collaboration at Microsoft, see the Directions Business Applications Roadmap.
