Consider the following scenario in a Microsoft Exchange Server 2019 or Exchange Server 2016 environment:
You have multiple domains (parent and child domains) in an Active Directory forest. An Exchange server is installed in one of those domains. Users are separately located in a sibling domain of the domain where the Exchange server is installed.
You notice that the RecipientViewRoot parameter in the Get-ADServerSettings cmdlet is set to the domain where the Exchange server is installed by default. This means that when you run the Get-Mailbox cmdlet, it will return mailboxes that are in that domain only.
You change the recipient scope to sibling domains by using the RecipientViewRoot parameter.
You run the Get-Mailbox cmdlet and expect to see the mailboxes of the sibling domains.
Unexpectedly, you see the mailboxes still from the domain where the Exchange server is installed.
Note There is a similar issue The recipient scope setting doesn't work for sibling domains in Exchange Server 2016 that was fixed in Cumulative Update 8 for Exchange Server 2016.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
Learn about the terminology that Microsoft uses to describe software updates.