Keep previous sort preferences for column headers
I prefer to have date sort with the oldest on top. Let's say I have my email sorted in that manner. If I click on Subject, it re-sorts by subject. That's fine. However, If I then click on the "Date Received" header, it automatically re-sorts with newest on top, and I have to click the column header again to sort with oldest on top. It would be nice to have the last order used for a column when one clicks the header to sort by that column. The email client I use for personal use (Postbox) does this, and it it very convenient.