Go to the next unread message through all folders

The Problem

I have a lot of folders and as the Mailspring doesn’t support saving filters or smart folders I have to manually go through all subfolders with unread items. It’s very uncomfortable.

Proposed Solution

I propose to add the button (with hotkey of course) “Next unread” which should open the next unread item even it is in another folder.

Alternative Solutions

I didn’t find any alternative.

(Originally posted by panter-dsd on GitHub.)