SPEventReceiverDefinition.SiteId Property
Gets the ID of the site collection in which the event receiver is registered.
Assembly: Microsoft.SharePoint (in Microsoft.SharePoint.dll)
Available in Sandboxed Solutions: Yes
Available in SharePoint Online
Users perform actions such as delete, update, check in, or convert on Microsoft SharePoint Foundation objects. When a SharePoint Foundation object has some action performed on it by the user, the object generates an event. The event that specified that an action occurred must be received by an event host that is specified by the site that is associated with this property.