If you are a fan of the 2-line, 3-column view first introduced in Microsoft Outlook 2003 and wished that Apple Mail supported it, you’re in luck. WideMail is an add-on for Mail that enables custom 3-column views, including the one used by Outlook/Entourage.
After downloading and installing the plugin, you may notice that the view does not yet show up properly. While it enables 3 columns automatically, an extra step is required to get the 2-line functionality. Simply right-click (or Command-click) on the column header and enable “WideMail Column.” You may also want to disable the other columns to get it to look right.
Before uninstalling, however, you will want to be sure you’ve re-enabled the Subject column, as there is no way to get that back after WideMail is removed.
Alternative: Letterbox
There is also another widescreen Mail plugin available called Letterbox. While this one came first, there was no Leopard compatible version for a long time, paving the way for the introduction of WideMail to satisfy user demand. Now, a Leopard version is available, and you may want to give it a try to see if it suits your taste.