In general, I like the preview pane and actually for most mail, read it in there.
BUT, I also, for example, skim through my junk mail folder just in case of false positives from the two layers of spam processing and then delete the garbage.
It appears that the process for displaying in the preview pane is simply show the message that is currently selected for preview.
The hitch comes that even after I've deleted the last message, the body associated with the message remains visible in the pane. This often leaves some graphic images in there! Granted, another "click" opening a different mailbox resolves that issue, but it's a nuisance.
Is it possible, therefore, on delete to clear the preview pane, before showing the "next message" ... it seems that since on deleting the last message, there's no next message, the preview pane is not cleared.
Stuart
Teco & EDT Rule