As the monitors in my life have gotten wider, I’ve longed for a Mail.app feature that’s baked-in to most other Mac email apps and RSS readers (as well as all the Microsoft email clients I’m aware of): the three-paned, widescreen format.
Prayers apparently have been answered in the affirmative with harnly.net’s Widescreen Mail.app plugin. On my 1440×900 MacBook Pro this works great, but it’s truly a godsend on my ginormous (and beloved) Dell UltraSharp.
This Mail.app plugin rearranges the interface into three vertical columns — so the message pane is to the right, rather than below, the message list.
On a widescreen Mac, this gives the email a more pleasing paper-like shape. You’ll probably need at least 1280 and perhaps 1440 pixels across for this arrangement to work for you.