I have a Cisco Unity 5.0 Build 5.0(1) integrated with CCM 4.1, I have an issue basically Old, deleted messages keep appearing in the list of unread messages. For example, I listened to the voicemail yesterday and there were apparently 12 unread messages however they dated back to December 6 when they have definitely been checked multiple times and cleared since then.
This can be possible if the deleted mail messages for the Unity Users are restored on the Exchange Servers.
Unity uses the Exchange Server to store the Voicemail messages for Unity users.
Please verify that the Exchange server mailboxes have not been restored to a previous date or if any of the users has manually attempted to restore his/her mailbox.In such a case, all the voicemails will also reappear in the inbox of the user.
If all the users on Unity are experiencing this, then it is complete mailstore restoration.Otherwise, check for individual mailbox restoration.
I hope it helps!!!
For the other part, if the messages are marked as unread on the mailbox on the Exchange Server, they will be listed as new messages when you login to the Unity TUI (Telephony User Interface).This again can be an outcome of restoring the old deleted messages.