You can think of a smart folder as a saved search that continuously and automatically updates so that you don’t have to redo a search. Follow these next steps to create a smart folder in Outlook for your voicemails.
Launch Outlook and expand the account you would like to create a smart folder for. At the bottom of each account tree, you'll notice a Search Folders icon.
Right-click Search Folders in the account that you'd like to apply the search to and Click New Search Folder...
In the Search Folder Criteria window, locate and click the Advanced tab at the top. Then, locate the field button and click on it. This will make a drop-down menu appear. In this menu, select All Mail fields. This will make a second drop-down menu appear. Locate Message Class and click on it.
Now you need to confirm that the information in the "Define more criteria" section is correct. It should read Field: "Message Class" Condition: "contains" and Value: "Cisco Unity Voice". Once you have confirmed this select "Add to List". Once this is done, click OK.