At work, I have selected an alternative view for my mail client. As I use Mozilla Thunderbird, the same thing should apply for Mozilla Mail. In the preferences, you can select a three-paned horizontal view. It’s great here on my 1600×1200 desktop, but I now run the window a bit larger (almost maximized — I did have it maximized earlier, but I don’t really care for maximized windows so I just made it take up most of the screen while unmaximized). The first column is for servers, each with multiple mailboxes over IMAP. The second column is the short header display (name, subject, date, status, etc.). In the third column, the actual email resides.

Since I have switched, I have discovered that I really like this alternative view. At first, I thought I’d hate it, but it has quickly grown on me, as I can see much more of the threading in the header region and also I can see most, if not all, of an actual message without scrolling.

If you have a decently large resolution and might happen to be running some version of Mozilla for mail, I suggest that you might try this layout for a little while (a couple of days, possibly) to see if you like it. I do. It makes tracking mailing lists much better (the various Fedora lists get lots of traffic).

Update: I have uploaded an example screenshot of my mail client demonstrating the new layout. (Yes, I did a lame blur-out-the-names effect for some of the lists and folders I have.)