I don't know much about disclaimer utilities, but *if* you can filter on the message class as set in Exchange, then you can exclude messages with the class "IPM.Note.Voice.Unity" (regular emails are just "IPM.Note"). This mechanism is commonly used to prevent voicemails from being archived or deleted by mailbox management add-ons.
I suspect the class might be being changed on your problem messages by the disclaimer process, which will cause Unity to not see it as a voicemail. You can view this class within Outlook 2010 by adding a column for it with the Field Chooser in your Inbox to verify.