Yahoo's spoof of the "From" header is an annoyance:

- clutters the message list displayed by KMail

- clicking on "From" in the message window does no longer open an editor window with "To" header set to the original sender, but the new mail goes to the spoofed address.

In mail sent from Yahoo servers the original "From" is now moved to “X-Original-From" x-header. So I want to replace the spoofed "From" by the value of “X-Original-From". How can I do this using KMail? Any other suggestion how handle this problem?