In a large Public Folder deployment, the public folder mailboxes hosting content could end up being geographically dispersed. As there is now no concept of Public Folder replicas, client applications will always connect to the Public Folder Mailbox hosting the content requested.
However, before content can be returned to the client, the Public Folder hierarchy has to be fetched. Outlook’s autodiscover process will return a random Public Folder mailbox for servicing the hierarchy. This means that in a large, dispersed deployment a non-optimal mailbox may be selected.
In this scenario, a Mailbox User can be configured to always retrieve hierarchy information from a specific Public Folder Mailbox. This can be done with the following PowerShell command:
Set-Mailbox <mailboxID> -DefaultPublicFolderMailbox <ChosenPFMailboxID>