How to Disable New Outlook for Users (Admin Guide)

How do you disable new Outlook for users across a tenant?#

There is no single switch. Disabling new Outlook for users is three separate decisions, and Microsoft ships a different control for each: whether classic Outlook offers the switch, whether the mailbox will open in new Outlook at all, and whether the app is on the device.

The fast route for most tenants is two policies: enable the cloud policy Hide the "Try the new Outlook" toggle in Outlook, and set Manage user setting for new Outlook automatic migration to 0. Then confirm nobody enabled Admin-Controlled Migration to New Outlook, which does the opposite job.

Need a block rather than a hidden button? Set OneWinNativeOutlookEnabled to false in Exchange Online. Either way, treat this as a dated delay: Microsoft supports existing classic installs through perpetual and subscription licensing until at least 2029, but these controls stop being the answer at cutover.

Before you start: name the scope you are blocking#

Most failed attempts apply a control at one layer and test the symptom of another. This is the tenant and device version — the single-machine route is in our companion post on stopping the Try the new Outlook toggle.

• User scope — Cloud Policy, ADMX and HKEY_CURRENT_USER values. Read by classic Outlook for Windows only.
• Mailbox scope — Exchange Online cmdlets. Follows the account onto devices you do not manage.
• Device scope — package removal and the Windows preinstall block. Says nothing about who signs in.
• Client scope — none of these registry paths exist on macOS, and legacy Outlook for Mac has its own October 2026 retirement.

Every lever, what it does, and where it lives#

Several of these sound alike, and two do the reverse of what an admin holding a fleet on classic wants. All checked against Microsoft's documentation in July 2026.

Hold a fleet on classic Outlook: the working order#

Work down the layers. Most organisations with an add-in dependency need only the first four steps, and all of them are reversible when the rebuild lands.

1. 1

   Confirm your builds support the toggle policy

   Channel minimums: Current Channel 2304 (build 16327.20214), Monthly Enterprise Channel 2303 (16227.20318), Current Channel Preview 2209 (15629.20058), Semi-Annual Enterprise Channel 16731.20504, or later in each case. Machines below the line ignore the policy silently.

2. 2

   Enable the toggle policy in Cloud Policy

   At config.office.com: Customization, Policy Management, Create. Search for Hide the "Try the new Outlook" toggle in Outlook, enable it, scope it to a pilot group. The same setting is in the Administrative Template files for Microsoft 365 Apps if you prefer Intune or Group Policy.

3. 3

   Set the automatic migration user setting to 0

   Unconfigured is not equivalent. Microsoft documents the underlying user setting as enabled by default, so leaving the policy unset means users can still be switched automatically.

4. 4

   Verify admin-controlled migration is off

   This is the one that catches people. If a predecessor enabled it, it installs new Outlook in the background, then runs a callout, a banner and a blocking prompt across three sessions. Set it to 0, leave the interval at 0, and note that step three does not cover it.

5. 5

   Add the mailbox block if a hidden button is not enough

   Set-OwaMailboxPolicy with OneWinNativeOutlookEnabled false covers existing and future mailboxes on that policy; Set-CASMailbox covers named mailboxes only, and blank equals true. While you are there, confirm HideClassicOutlookToggleOut is false, or anyone who does reach new Outlook is stranded.

6. 6

   Decide separately whether the app stays on the device

   Nothing above uninstalls anything. Remove-AppxProvisionedPackage with the package name Microsoft.OutlookForWindows stops updates reinstalling it, Remove-AppxPackage clears user installs, and blocking Microsoft Store access closes the last door.

7. 7

   Pilot on one machine, restart, test across sessions

   Policy refresh, app launch and a restart are all involved. Microsoft notes the logic pulling a user back out of new Outlook runs when the registry key is read, typically at restart. Reopening Outlook once is not a valid test.

Three independent layers, each control touching exactly one: the toggle is the user layer, the mailbox block is the account layer, package removal is the device layer. Hide the toggle and still find someone in new Outlook? That is not a bug, that is the second layer.

Where Microsoft's own documentation disagrees with itself#

A value copied from the wrong page and pushed fleet-wide produces the opposite of the intended result, so this is worth two minutes.

The Control installing and using new Outlook page introduces its registry sample as the way to hide the toggle — and that sample sets HideNewOutlookToggle to dword:00000000. The Exchange Online page, authoritative for this value, labels 1 as Hide and 0 as Show. Only one can be right. Follow the Exchange Online article, and prove it on one machine before scoping wider.

Two smaller ones on the migration-policy page: it names the mailbox policy HideClassicOutlookToggleOut in its instructions and HideClassicOutlookToggleOutlook in its sample scenarios, and its .reg blocks for NewOutlookAutoMigrationRetryIntervals use a colon rather than an equals sign, which will not import.

Client and platform differences#

Much of the confusion here comes from applying a classic Outlook setting and then testing in something that never reads it.

It is applied and users are still in new Outlook. Why?#

Four causes cover nearly all of it. Work top down.

How long do these controls actually buy you?#

Three stages: opt-in, where new Outlook is off by default; opt-out, where it is on by default but users can revert; and cutover, where reverting is not possible. The Learn page dated February 2026 still puts new Outlook in opt-in, with at least 12 months of notice before opt-out reaches managed enterprise plans and before cutover reaches production rings.

Be careful what you plan against. Message centre post MC949965, updated 20 February 2026, moved the start of enterprise opt-out to 1 March 2027 — a year later than the date still circulating widely. Message centre posts are tenant-scoped and never appear on Learn, so confirm the date in your own admin centre rather than trusting any article, this one included.

So you have years of runway with a year's warning, and classic installs supported until at least 2029. Spend it on what decides your real switch date: an inventory of the COM add-ins, VBA macros and custom forms your users depend on, because those are not coming to new Outlook.

The short version#

Hide the "Try the new Outlook" toggle in Outlook, Manage user setting for new Outlook automatic migration set to 0, and a check that admin-controlled migration is off. That is the tenant-wide answer for most organisations, and it needs no registry editing.

Add OneWinNativeOutlookEnabled set to false if you need a block rather than a hidden button, and remove the provisioned package if the app should not be on the device at all. Test each on one machine, restart, verify across sessions.

Disclosure, since you are reading this on our site: we build AI Emaily, an email client for Outlook, Microsoft 365, Gmail and IMAP accounts. It has nothing to do with this task and nothing above depends on it.