Digital recommends that you disable this setting if you have numerous messages in your folders. With this option disabled, you must choose the Renumber messages menu item from the Main Inbox window's Maintenance menu to renumber the messages in a folder. Put deleted messages into wastebasket instead of deleting immediately. With this option enabled, Mail moves deleted messages to the FoNt5wastebasket folder, allowing you to retrieve them if you deleted them by mistake. Disabling this option causes Mail to irretrievably delete messages.
Buttons affect the current message if no messages are selected.
With this option enabled, Mail highlights all buttons on a selected message whether the button function is available or not. With the button disabled, Mail highlights only those buttons that are functionally available. Normally, this button is disabled. Open Subfolders when drawer is open. With this option enabled, Mail opens all folders in a drawer when you open the drawer.