Exit/Quit when main window closes
* The verb differs depending on your operating system: Exit on Windows, Quit on Mac OS and Linux.
When the main window closes, all associated application windows will close with it; these will be restored when the program is restarted.
The behavior of this feature is slightly different depending on what UI style you’re running. In 2-pane mode, the main window is considered to be the mailboxes window (aka the mailbox folder tree). In 3-pane mode, it is the first mailbox window that is opened. If your mailboxes are set to open in tabs, there is only one window. If you have chosen to run 3-pane mode with 2-pane behavior, opening mailboxes in their own separate windows, you will have to personally keep track of which mailbox window was opened first.