Can't configure Exchange Online mailbox in Outlook Desktop

Last Updated: October 27, 2022

ISSUE

Users may be unable to configure mailboxes in Outlook for Windows. An error during the Autodiscover flow will prevent the process from completing.

Through the Outlook Connectivity test, affected users will get a 603 error:

<Autodiscover xmlns:xsd=http://www.w3.org/2001/XMLSchema xmlns:xsi=http://www.w3.org/2001/XMLSchema-instance xmlns=http://schemas.microsoft.com/exchange/autodiscover/responseschema/2006>
<Response>
<Error Time="11:20:40.9842288" Id="1507709422">
<ErrorCode>603</ErrorCode>
<Message>Deleted objects will not be found with a session scoped to TenantLocal or AllTenants, unless search is scoped to Deleted Objects container.</Message>
<DebugData />
</Error>
</Response>
</Autodiscover>

Get-Mailbox will point the SharingPolicy to a deleted object (eg. Default Sharing Policy DEL:12345b67-1ab0-1234-abc1-ab1c23456789).

STATUS: WORKAROUND

This issue is expected to be fixed by late November 2022. The fix will be available in Exchange Online service build 15.20.5784.000. To check the service version from Outlook, use the Connection Status dialog and see the Version column, Description of the Connection Status dialog box - Outlook | Microsoft Learn.

In the meantime, if your organization is affected, Administrators can use the following steps to fix it manually:

Connect to Exchange Online PowerShell: Connect to Exchange Online PowerShell
Confirm that Get-Mailbox is pointing the SharingPolicy to a deleted object by running:

Get-Mailbox -ResultSize 10 |fl *sharingpol*
Restore the Default SharingPolicy by running:

New-SharingPolicy -Name "Default Sharing Policy" -Domains '*:CalendarSharingFreeBusySimple', 'Anonymous:CalendarSharingFreeBusyReviewer' -Enabled:$true -Default:$true
Confirm that Get-Mailbox is not pointing the SharingPolicy to a deleted object anymore:

Get-Mailbox -ResultSize 10 |fl *sharingpol*
Configure the mailbox in Outlook should work again.