如何防止ASP.net WP终止错误

I have some code in my ASP.net MVC project which asynchronously dispatches a message. Under certain circumstances that code can fail and cause an unhanded exception. I don't have direct access to the code which is throwing the exception or the code which is generating the thread so I'm unable to catch and handle the error there. I have tried catching at the Application_Error level in the Global.asax but that function is only thrown for page errors and not for background errors. I also tried catching in an HTTP module by implementing OnUnhandledException but I could find no way to catch the exception and prevent the worker process from existing in there. I have some code in my ASP.net MVC project whic