@artfudd -- just click on any of the column-headings to sort on that column, e.g., A-to-Z. Click again to sort Z-to-A.
If you click on "Date", you can get newest-to-oldest. Another click gives you oldest-to-newest.
If you click on "Size", you can find the largest messages. Then, you may delete some of them, to stay under your 1000 Mbyte "quota".