Microsoft is making it easier to move between Outlook Classic to the new Outlook for Windows. Starting October 2025, accounts and settings for Microsoft-hosted mailboxes in Classic will automatically transfer to the new app in the background—no manual setup required. It promises a seamless transition, while admins retain full control over opt-out policies and rollout settings.
It means that Microsoft hosted email accounts setup in Outlook classic will automatically be added to new Outlook as well. This is in addition to the current account migration for Microsoft hosted accounts if you choose the ‘New Outlook’ toggle in Outlook classic.
Fear not: this doesn’t change any existing settings, force you into the new Outlook, or alter your defaults. You’ll simply continue using Outlook without the extra setup steps—unless you decide otherwise.
How It Works & What You’ll See
- If you’re already signed in to the new Outlook, your primary account remains the same.
- New accounts added in classic Outlook will appear as secondary accounts in the new Outlook.
- Shared mailboxes and delegate permissions are preserved.
- The setup happens when launching classic Outlook; users launching the new Outlook directly will still have access to their familiar accounts and settings.
- By default, automatic setup is on, and you’ll receive an in-app notification in classic Outlook.
Important Dates to Keep in Mind
- Rollout begins: October 2025, via Current Channel (General Availability)
- Migration opt‑out deadlines remain unchanged:
- EDU tenants: January 2026
- Enterprise tenants: April 2026
Admin Controls & Opt‑Out Policy
Admins have the power to manage this behavior using either registry settings or modern admin tools. The relevant details:
- Registry path:
HKEY_CURRENT_USER\Software\Policies\Microsoft\office\16.0\outlook\preferences - Registry key:
"NewOutlookAutomaticSetupUserSetting"- Not Configured (default): Users can opt out via Outlook options (enabled by default)
- Enabled: Automatic setup enforced; user cannot opt out
- Disabled: Automatic setup prevented; user cannot opt in
Other admin management options include:
- Cloud Policy via Microsoft 365 Apps admin center
- Group Policy (ADMX templates)
- Microsoft Intune (administrative templates)
