Problem with HTTP POST

While making postdata, if i use & as boundary, everything seems to be fine. If i change that to some other string, say &&, it fails with unknown error, once i get response.

i use:

request.Headers["boundary"] = "&&"; //--> which leads to a failure(exception)

when i use & as boundary in postdata, even if don't mention in 开发者_高级运维request.Headers["boundary"], result is same(success).

Can somebody throw some light on how to set boundary?

Thanks for help.

MSDN seems to suggest that Boundary isn't a header that you can set.
List of supported headers: http://msdn.microsoft.com/en-us/library/system.net.httprequestheader(v=vs.95).aspx