Invert sorting of mails in mailbox

[ebroda]

Currently, all mails are ordered historical, with the oldest one first (or maybe not explicitely ordered but by database sorted). I'd suggest to change that order to have the newest entries on top, so that I don't need to go to the last page if there are more than 30 messages.

And it's probably better to update this in the backend than in the frontend.

[deinelieblings]

The code is still a little difficult in the backend code. The messages are simply attached to the mailbox. A GET for messages with sort filter limit would definitely need to be built in the backend at this point.
So the first step would be to sort it in the frontend and include the changes for the backend in a new issue. Does that make sense?