It sounds to me that you are a voicemail only implementation and not Unified messaging because typically users will delete their deleted items folder in Outlook and avoid this issue.
In this case, there are two setting that you should know about.
1. The first is the one that will modify the behavior you describe on a class of service basis. Within a suspect class of service in the Unity System Admin, browse to Messages. Here you will see a setting "Deleted messages are copied to the deleted items folder ". If this is checked, Unity will place a deleted message in the "Deleted Items" folder within the user's Exchange mailbox. In a VM only installation, it is often an overlooked setting because people forget about the underlying message store. If it is unchecked, messages will be immediately and permanently deleted upon hang up.
2. The second is in the subscriber profile. This setting controls only whether the user is prompted to confirm message deletion while in the TUI, not where the message goes, so will not solve your problem. I only mention it because some users can be annoyed if they have to confirm each message deletion, if configured this way.
Navigate to Subscriber: Conversation. Scroll roughly half way down and look for a setting called "Confirm deletions of new and saved messages". Ensure that your templates are configured the way you want as well.
If you wish to configure this second setting on a global basis, there is an Advanced Tool Setting on the Unity server to modify the behavior. If this is needed, respond to this message and I'll tell you about it.
Hope all this helps!
