How can I move Mail’s Preview Pane to the right side of the window?
If you prefer to view your Mail messages on the right rather than at the bottom (Mail’s default), check out Aaron Harnly’s free Letterbox (harnly.net/software) or Dane Harnett’s WideMail (payment requested; www.daneharnett.com/widemail). Not only do these Mail plug-ins allow you to shift the Preview Pane, but they also perform some additional tricks.
With Letterbox, you can tweak the appearance of your message list by choosing to have alternating rows appear in colour, or adding line dividers between rows. And you can set the Preview Pane divider line to normal or hairline. WideMail offers the same customisations as Letterbox, along with a few more options. You can choose to show or hide relative dates (Today, Tomorrow, or Yesterday, instead of specific dates), add vertical – as well as horizontal – lines between rows and columns in your message list, change the colour of those grid lines, and alter the spacing between rows.
If you don’t like the way Apple Mail displays your email messages by default, use Mail plug-ins Letterbox and WideMail to shift the Preview Pane to the right side of the window