As an alternative to the mouse you can use the following keys:
To switch between the menu bar, the folder view, the sidebar, and the display area, use [Ctrl]+[F6] on Windows and Linux systems, [F6] on MacOS systems.
To select an app in the app launcher, use [Down arrow] or [Up Arrow].
To select a function, an input field or a checkbox, use the [Tab] key. The selected element will be highlighted.
With [Shift]+[Tab] you can select elements in reverse order.
To execute the function selected, press [Enter].
To enable or disable a selected checkbox, press the [Space bar].
To toggle the checkboxes, use the cursor keys.
To move the cursor within input fields, use the following keys: cursor keys, [Home], [End].
To browse the folder view or the sidebar, use the following keys: [Page up], [page down]
To open or close a folder in the folder view, use the left or right arrow key.
To select elements in the folder view, the toolbar, the sidebar or the display area, use the cursor keys.
To close a pop-up or cancel a window, press [Esc].
To delete the selected emails, folders or files press [Del] or [Backspace].
To move selected emails to the folder, press [a].
To select all objects in a list, press [ctrl]+[a]
Parent topic: General Description of the User Interface