In BlackBerry Enterprise Sever 5.0 SP3 the BlackBerry Server stores the Unread Marks Table as a collection of UNID's. This properly captures the state of email message ID's across multiple mail file replicas. This process is achieved by leveraging a new API that Lotus has created for RIM called NSFGetMultNoteInfoByUNID.
To validate that this change is functioning, following the installation of BlackBerry Enterprise Server 5.0 SP3 the following table should appear in the User Info View
of each users BlackBerry State Database, under the respective User Info Document > UnreadMarksTableUNID
With this change, there will be 2 attachments in the UserInfo document now in the State database: (1) UnreadMarksTable (2) UnreadMarksTableUNID
See KB25798 for more information.
Link: KB25798-Mail Server failover causes the BlackBerry Enterprise Server to process excessive Read/Unread marks, which may contribute to BlackBerry Mail Delays