Non-Unicode data file or running Outlook in non-Unicode mode
It has no way to convert Outlook in non-unicode to a uUnicode-capaple file. But you can create a new data file on Microsoft Outlook folders file that uses (.pst) format which supports Unicode. You can then import the items to the new Outlook Personal Folders file from the old data file using (.pst)
To create new data file, Click on File menu, then View. Click on Outlook Data File.
Create Microsoft Outlook Personal Folders File that can handle greater storage for folders and items. That can also supports multilingual Unicode data, then click OK.
Type the name of the file in File Name box and click OK
In the Name box, set a name for (.pst) folder and select the options you want and click OK.