How to dump ASP.NET Request headers to string

I'd like to email myself a quick dump of a GET request's headers for debugging. I used to be able to do this in classic ASP simply with the Request object, but Request.ToString() doesn't work. And the following code returned an empty string:

using (StreamReader reader = new StreamReader(Request.InputStream))
{
    string requestHeaders = reader.ReadToEnd();
    // ...
    // send requestHeaders here
}