How to get compact layout of mail preview pane?

Recently changed my laptop,
now facing this issue in new emclient setup

i have 3 pane layout , in second vertical pane (sender list preview pane)it shows
Sender, Subject , Date etc.
i am able to hide Subject from column, but it does not save the space there. It shows blank space.

in my earlier setup there was no subject and it countained nearly double number of mail previews.

kindly guide.