A customer asked about a situation in which they’re unable to remove mailboxes from users’ Outlook profiles. In this case they were shared mailboxes and appeared in the left pane of Outlook. Although this case was for shared mailboxes, the cause and solution apply equally to user mailboxes. This can occur for on-premises Exchange Server and cloud-hosted mailboxes in Exchange Online.
In the Outlook account settings for the user, the shared mailbox does not appear as an additional mailbox.
The reason that the shared mailbox appears in Outlook, but does not appear in the Outlook account settings, is that auto-mapping is enabled by default when a user is granted access to a shared mailbox or to another user’s mailbox. When auto-mapping is enabled, Outlook receives extra information in the Autodiscover response that tells it to open the additional mailbox.
The auto-mapping option can only be configured at the time the permissions are granted. If you want to remove auto-mapping for a user’s access to a shared mailbox, then you must remove their mailbox permissions and then re-add the permissions again. Also, this will need to be performed using PowerShell, because the Exchange Admin Center doesn’t expose the option to enable or disable auto-mapping when configuring mailbox permissions.
To remove and re-add a user’s mailbox permissions using PowerShell, we can use the following steps. First, for an on-premises mailbox open the Exchange Management Shell, or for a cloud mailbox connect to Exchange Online.
Using the example from the screenshot above, the user in question is Adam Wally, and the shared mailbox is named ShareOnPremMailbox. Use Get-MailboxPermission to check that the permissions have been granted as mailbox permissions.
[PS] C:\>Get-MailboxPermission -Identity SharedOnPremMailbox -User Adam.Wally | fl
RunspaceId : 1af8b9f0-d64e-4cb8-b8e1-e905c6923ed5
AccessRights : {FullAccess}
Deny : False
InheritanceType : All
User : ESPNET\adam.wally
Identity : exchangeserverpro.net/Company/Head Office/Shared/SharedOnPremMailbox
IsInherited : False
IsValid : True
ObjectState : UnchangedNext, use Remove-MailboxPermission to remove the mailbox permission for the user.
[PS] C:\>Remove-MailboxPermission -Identity SharedOnPremMailbox -User Adam.Wally -AccessRights FullAccess Confirm Are you sure you want to perform this action? Removing mailbox permission "SharedOnPremMailbox" for user "Adam.Wally" with access rights "'FullAccess'". [Y] Yes [A] Yes to All [N] No [L] No to All [?] Help (default is "Y"): y
Finally, re-add the mailbox permission by running Add-MailboxPermission, this time using the -AutoMapping parameter to disable auto-mapping.
[PS] C:\>Add-MailboxPermission -Identity SharedOnPremMailbox -User Adam.Wally -AccessRights FullAccess -AutoMapping:$false
The change will not immediately be obvious to the end user, because there is a delay before their Outlook client picks up the change via Autodiscover. When Outlook receives the updated Autodiscover response, it will remove the auto-mapped mailbox from the user’s Outlook profile. If the user needs to access the mailbox for anything, they must add it to their profile, or open it via the Outlook File menu.
As a side note, there’s nothing in the Get-MailboxPermission output that will tell you whether a user who has access to a mailbox will be auto-mapped. However, for on-premises mailboxes you can query the Active Directory user object properties to determine who will be auto-mapped to a mailbox. The property that stores this information is named msExchDelegateListLink, and it can be queried using Get-ADUser. For example, to view the list of auto-mapped users for a mailbox named Payroll, we can run the following command.
[PS] C:\>Get-ADUser -Filter {Name -eq "payroll"} -Properties msExchDelegateListLink | Select -ExpandProperty msExchDelegateListLink
CN=Bruce.Thillainayagam,OU=Users,OU=Head Office,OU=Company,DC=exchangeserverpro,DC=net
CN=Alex.Heyne,OU=Users,OU=Branch Office,OU=Company,DC=exchangeserverpro,DC=net
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