I'm not the grandparent poster, but I'm not sure if this is what they had in mind by "filtering rules". When I read the comment, I immediately thought of how I use procmail for live sorting of incoming mail, but I also occasionally pull out al(pine) for various manual sorting/rearranging tasks. I've always found its "broaden/narrow selection + zoom" tools to be pretty powerful. (Maybe mutt has tools of similar capability; I don't know.)