Adding notifications on server exceptions to a C# ASP.NET MVC application allows administrators to be notified in case of any issues with the server. The application uses the Twilio REST client to send SMS and MMS notifications, and it handles application-wide errors by forwarding them to a list of administrators who have provided their phone numbers. The notification system is configured using a CSV file that contains the administrator's names and phone numbers. The error handling process captures application-wide errors and sends a custom alert message to each administrator in the list, including the exception details and a link to New Relic for further details.