I assume you are using the Classic View and at the top of your window you have the list of emails in the folder and at the bottom you have the message pane with the content of the selected mail. If you move your mouse pointer slowly up or down from one pane to the other, at the point where they join the pointer should become a double-headed (up/down) arrow. Hold the left mouse button down while it looks like that and you should then be able to drag the border upwards.

Unfortunately I don't get a "double headed arrow" when slowly moving the cursor over the margin boundary in "Classic" view or any other combination of views, tools help etc. To be clear I am talking about the bottom pane just above "today pane" and I want to shrink one or both of the panes above it to read the message pane all at once or more at once. I tried shrinking the top pane which reduced the number of messages displayed, but, I actually like displaying more message titles. The middle pane often contains just code and is of little use to me so it is the one I want to intrude upon (shrink) while expanding the message pane. I hope this is enough information' Thank you, Chris

re :The middle pane often contains just code and is of little use to me so it is the one I want to intrude upon (shrink) while expanding the message pane.

It sounds as if you have full headers displaying, so try this; 'View' > 'Headers' > 'Normal'