You deploy an account forest and a resource forest in a Microsoft Exchange Server 2013 environment.
You configure a linked mailbox in the resource forest for a user in the account forest.
The sAMAccountName attribute of the linked mailbox account differs from the sAMAccountName attribute of the user in the account forest.
The user tries to access the linked mailbox through POP3.
In this scenario, the user cannot access the linked mailbox.
For example, you create a user account in the account forest that is named Contoso\Pop, and create a linked mailbox in the resource forest that is named Fabrikam\Pop_Fab. In this situation, the user cannot access the linked mailbox by using POP3. However, if the linked mailbox is named Fabrikam\Pop, the user can access the linked mailbox by using POP3.
This issue occurs because Exchange Server 2013 searches Active Directory by a specific account name property. Therefore, Exchange Server 2013 cannot find the linked mailbox if the property of the linked mailbox differs from the user’s property.
To resolve this issue, install the following service pack:
2926248 Description of Exchange Server 2013 Service Pack 1
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information about how to manage linked mailboxes, go to the following Microsoft website: