MVC3 Passing ControllerContext to thread? - asp.net-mvc-3

Question

I am using Rotativa in my MVC3 app to generate pdfs into a memory stream which is then emailed out as an email attachment. This works fine but it is quite slow (~5-7 seconds with just 1 user) so I've been trying to put it into a separate thread so the user doesn't get stuck with a huge delay.
The problem I've been facing is that Rotativa requires the Controller Context to generate the data into the memory stream, which means that if you try to put it in a separate thread and return a notification to the user then the context is disposed and the pdf generation will fail.
Unfortunately I do an email validation check on the server-side and return a true/false where appropriate, false will prompt the user to fix it and try again. This means I can't just assume that the email is always valid (I could do it by jquery, but if they turn it off and try to submit they won't get an error message).
So far I have tried:
Creating a new thread and passing the context in
Duplicating the context by copying it to a new variable
Serializing the context, passing the stream to the new thread and de-serializing (unfortunately the context is not serializable)
Has anyone got any other ideas?

Answer 1

Here is what I do to run a long process in the background with context. I'm using custom sessions backed by a database. You'll need to pass whatever values you need into the "background" action.
using (var client = new WebClient())
{
var values = new NameValueCollection
{
{ "sessionid", DataSession.Id.ExtractSid() }
};
client.UploadValuesAsync(new Uri(Url.AbsoluteAction("ResultsCallback", "Quote")), values);
}