This is the role of the new concept of local host. The local host is an object that resides in the PostSharp application domain between the PostSharpObject and the host object residing in the host application domain (IPostSharpHost). The whole communication between the PostSharpObject and the remote host now goes through the local host. We provide a default implementation in the PostSharpLocalHost class, but you can override it and pass your own implementation using the LocalHostImplementation property of the PostSharpObjectSettings object.