Maybe I`m just the message queen here, because I`ve had to deal with a full mailbox like 3 times, but ...
When you click on the Sender, so you are sorting by name, it sorts them by name on the first page.
But then you click to the next page and the by-name sorting reverts to normal sorting, second page.
So ... it would be a lot easier to clear out things if I could make it stay sorted by person. And then I`d stop using up all the server space here because it keeps my message in my box and in the other person`s send box until I delete. OK, maybe I`d clean it out ... maybe if it was easier.