I think popdiga is not using the preview pane, JoeC.
popdiga, open one email, drag it to the size you want, minimise it to the taskbar, open a second email, drag it to the larger size, if it isn't already that larger size, minimise it to the taskbar also, then close the first one you dragged larger. Now open a third email, it should open at the larger size and windows will remember this and open them at that size from now on.
My current set up shows two 2 Windows one for "Folders" and the other shows the email headings. Using View, Layout does not help in that I could get the " 3 Windows view" ie Folders, Email Heading and the Emial message below that.
I have to click twice to open an email and then it only opens it in a minimised form ie not full screen. If I maximise it etc as suggested windows does not remember that I want to have it maximise every time I reopen an email.
What I want is to see a maximised view of my email every time I open it, without having to click on the maximise button at the top left of the Window to make it a full screen view. Hope this clarifies my problem