How do I return to the preview panel in Mail?
Some time ago I followed instructions from a community member on how to turn off the preview panel in mail by sliding the divider between the mail list and the preview panel all the way to the right. This worked however I can't figure out how to reverse the action? How do I get my preview panel back?
MacBook Pro (15-inch, Late 2016), macOS Sierra (10.12.3), Touchbar