Web Server (IIS) Role Service Windows Authentication was removed either by an Administrator or Policy.
1. Open Server Manager
2. Scroll down to Web Server (IIS) | Role Services
3. Click Add Role Services
4. Scroll down to Security and ensure "Windows Authentication" is selected, if not then select it and Click Install.
If this has been added, Make sure that the MessageStats virtual Directory is set to use Windows Authentication and you can disable the rest of the Authentication methods.