When an HTTP POST is redirected to GET, what happens to the body of the POST?

Question

As per my previous question, I need to redirect an HTTP POST request to a different server. I believe this can be done using HTTP response headers from php, but I understand the

Answer 1

The POST data vanishes. Unless the redirecting script takes steps to push the POST data into the GET's URL or into a cookie, the data's dead and gone.

This is somewhat by design. Most browsers limit the length of a URL, and POSTs have effectively no limit to the size of the data being POSTed, so you wouldn't want that 500megabyte file you just uploaded appended to the GET url's query line.