My mail forwarding service has recently started adding a "Resent-From" header to all the messages, and I'm trying to filter this out in Mail.app.
I go into Preferences -> Viewing and select "Show message headers: Custom...". The list is initially empty, so I add "From", "To", and "Subject".
When I then view messages, I still see other headers like "Resent-From" and "Reply-to". And if I go back into Preferences and click on that dropdown again, the list of headers is empty again.
How do I get this to work properly?