Trim Subject Line

You can accomplish this with a small amount of programming. See https://postieplugin.com/postie_post_before/

I take it something like this would go into the site functions.php?

add_filter(‘postie_post_before’, ‘my_postie_post_before’);

function my_postie_post_before($post) {
if (strpos(strtolower ($post->$post_title), ‘fw: ‘) !== false)
$post->$post_title = substr ( $post->$post_title , 5)
return $post;
}

Yes, but remember the $post is an array not an object.