[Setting] Extension Name [Description] 
Specifies the delivery extensions that are available to the report server. Reporting Services includes default delivery extensions for Report Server Fileshare, Report Server Email, NULL delivery provider, and SharePoint Delivery. Report Server Email requires additional configuration before it can be used. The NULL delivery provider is supported for data-driven subscriptions only. SharePoint delivery is available only when you configure a report server for SharePoint integrated mode; you can ignore it if the report server runs in native mode. For more information about server modes, see Deployment Modes for Reporting Services. For more information about delivery extensions, see Delivering Reports Through Subscriptions.