Expanded columns in folders pane - Thunderbird

In the folders pane in Thunderbird, you can display the number of unread messages, the total number of messages, or the size of the mail folder. To do so:

• First go to Tools > Options > Advanced > General Settings, and check the box for "Show expanded columns in the folder pane." Click OK. This will cause a small drop-down marker to appear in the top-right corner of the folders pane.

• By clicking on this drop-down marker, you can then select Unread, Total, and/or Size to be displayed.