You could use the classic MDI mode which just lists the folders, double-click on a folder then the message list displays.

or

You could drag the dividing bar between the message and preview all the way to the bottom. Now you get the display you like, double click on a message and you can read.

IMHO - the classic MDI mode is the best. YMMV

I want to set Pegasus so I never get the "preview" window below the list of messages. The List / Preview button shuts off both right hand windows. That is not what I want. On the left I want to have the list of folders, on the right just the list of messages. I do not want any message to be opened in the bottom half of the right screen ever. I am fed up with having to turn off Preview mode every time I start Pegasus. Since I do most of my work on a laptop which is restarted several times a day, leaving Pegasus open constantly is not an option. Is there a way for the user to do this?