7 votesDerek R commented
There is already a select all button. If you're in a folder, look at the top of the email list. To the left of the name of the folder is a check mark inside a circle. If you click that, it will select all emails in the folder.
Alternatively, you can also use the Ctrl+A keyboard shortcut instead.
379 votesDerek R commented
In the folders pane, we have the "Favorites" section and the "Folders" section. Most of the folders I care about are in the Favorites section, but I have a bunch of folders under the Folders section -- more than can fit on the screen. I regularly have to scroll down thru all my folders, several times a day, just to make sure none of them have new emails in them.
It would be really nice if the "Folders" heading had an unread-email counter next to it, so I could see at a glance if any folders have unread emails, rather than having to scroll through them every time.