Display Three Line Autopreview For. The status bar is located in the lower right-hand corner of the application window. This is why you need to optimize your subject line to display well on all email clients.
LINETYPE3DPLINEOFF turns off display linetype display. If the ShowHide Lineweight button is not visible click Customization the right-most button on the status bar to add it to the status bar. If you are using 2018 try LINETYPE3DPLINEON.
In Outlook 2013 and Outlook 2016 you can configure Message Preview to show 1 2 or 3 lines of preview text for all messages.
Neither of these commands are in the Help system. Instead all I can do is to show a field in each row. If the ShowHide Lineweight button is not visible click Customization the right-most button on the status bar to add it to the status bar. Bring back the Show AutoPreview only for unread messages feature.