Enable or disable employee access to the new Outlook for Windows

The new Outlook for Windows is enabled by default for all users with an Azure Active Directory account. You can use Exchange Online PowerShell to prevent or allow access to mailboxes by the new Outlook for Windows.

What do you need to know before you begin?

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Enable or disable the new Outlook for Windows for an individual mailbox

In Exchange Online PowerShell, use the following syntax:

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

<MailboxIdentity> is any value that uniquely identifies the mailbox. For example:

  • Name
  • Alias
  • Email address
  • User ID

This example disables the new Outlook for Windows for the specified user.

Set-CASMailbox -Identity colin@contoso.onmicrosoft.com -OneWinNativeOutlookEnabled $false

To enable the new Outlook for Windows for the mailbox, use the value $true for the OneWinNativeOutlookEnabled parameter.

Enable or disable the new Outlook for Windows for multiple mailboxes

You can use the Get-Mailbox, Get-User or Get-Content cmdlets to identify the mailboxes that you want to modify. For example:

  • Filter mailboxes by attributes: This method requires that the mailboxes all share a unique filterable attribute. For example:

    • Title, Department, or address information for user accounts as seen by the Get-User cmdlet.
    • CustomAttribute1 through CustomAttribute15 for mailboxes as seen by the Get-Mailbox cmdlet.

    For more information, see Filterable Properties for the -Filter Parameter.

    The syntax uses the following two commands: one command to identify the mailboxes, and the other to enable or disable the new Outlook for Windows for the mailbox:

    $<VariableName> = <Get-User | Get-Mailbox> -ResultSize unlimited -Filter <Filter>
    $<VariableName> | foreach {Set-CasMailbox -Identity $_.MicrosoftOnlineServicesID -OneWinNativeOutlookEnabled <$true | $false>}
    

    This example disables the new Outlook for Windows for all mailboxes whose Title attribute contains "Vendor" or "Contractor".

    $Mgmt = Get-User -ResultSize unlimited -Filter "(RecipientType -eq 'UserMailbox') -and (Title -like '*Vendor*' -or Title -like '*Contractor*')"
    $Mgmt | foreach {Set-CasMailbox -Identity $_.MicrosoftOnlineServicesID -OneWinNativeOutlookEnabled $false}
    
  • Use a list of specific mailboxes: This method requires a text file to identify the mailboxes. Values that don't contain spaces work best (for example, the user ID or email address). The text file must contain one mailbox on each line like this:

    akol@contoso.com
    ljohnston@contoso.com
    kakers@contoso.com

    The syntax uses the following two commands: one command to identify the mailboxes, and the other to enable or disable the new Outlook for Windows for the mailbox:

    $<VariableName> = Get-Content "<text file>"
    $<VariableName> | foreach {Set-CasMailbox -Identity $_ -OneWinNativeOutlookEnabled <$true | $false>}
    

    This example disables the new Outlook for Windows for the mailboxes specified in the file C:\My Documents\Management.txt.

    $Mgrs = Get-Content "C:\My Documents\Management.txt"
    $Mgrs | foreach {Set-CasMailbox -Identity $_ -OneWinNativeOutlookEnabled $false}
    

Verify access to mailboxes by the new Outlook for Windows

To verify the new Outlook for Windows is enabled or disabled for a specific mailbox, replace <MailboxIdentity> with the name, alias, email address or user ID of the mailbox, and run the following command:

Get-CASMailbox -Identity <MailboxIdentity> | Format-List OneWinNativeOutlookEnabled

The value False for the OneWinNativeOutlookEnabled property means the new Outlook for Windows is disabled for the mailbox. True or absence of value means it is enabled.

To verify if the new Outlook for Windows is enabled or disabled for all mailboxes, run the following command to verify the value of the UniversalOutlookEnabled property:

Get-CASMailbox -ResultSize unlimited -Filter "RecipientTypeDetailsValue -eq 'UserMailbox'" | Format-Table Name,PrimarySMTPAddress,OneWinNativeOutlookEnabled