Is it safe to Enable employee access to the new Outlook for Windows?

Carlos Lino 6 Reputation points


I have some users who are not enable the new Outlook, others are with no issues and they have the same settings. Why?

If safe to run this script?

Set-CASMailbox -Identity <MailboxIdentity> -OneWinNativeOutlookEnabled <$true | $false>

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Microsoft 365
Microsoft 365
Formerly Office 365, is a line of subscription services offered by Microsoft which adds to and includes the Microsoft Office product line.
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Microsoft Exchange Online Management
Microsoft Exchange Online Management
Microsoft Exchange Online: A Microsoft email and calendaring hosted service.Management: The act or process of organizing, handling, directing or controlling something.
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  1. Faery Fu-MSFT 16,816 Reputation points Microsoft Vendor

    Hi @Carlos Lino ,

    There could be several reasons why some users are unable to enable the new Outlook even though they have the same settings. Here are a few possibilities:

    1. Outlook Desktop Registry Key: The new Outlook for Windows is enabled by default for all users with a Microsoft Entra account and Exchange Online account. However, the Outlook Desktop registry key can be configured to enable or hide the New Outlook toggle.
    2. Exchange Online PowerShell: This can be used to prevent or allow access to mailboxes by the new Outlook for Windows.
    3. Software Version: If users are running an older version of Windows or Outlook, they may not be able to enable the new Outlook.

    As for the script you’ve mentioned, it is a PowerShell command used to enable or disable the new Outlook for Windows for an individual mailbox.

    Before running this script, please ensure the following:

    1. Permissions: Make sure you have the necessary permissions to perform this procedure.
    2. User Notification: Inform your users before making changes to their mailboxes.
    3. Backup: Always back up any important data before running scripts.

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