Here’s a simple timesaver for those of you using Mail under OS X 10.4 (tested under 10.4.8, but it should work on older 10.4.x releases). In Mail, you can view your messages in a threaded mode, whereby Mail attempts to group messages in one conversation together into one collapsible group (in the View menu, select Organize by Thread). With all related messages grouped and collapsed, your inbox appears much neater, and it’s much simpler to follow all the emails in a given exchange.
But if you’re a keyboard addict, as am I, there used to be an annoying glitch in the keyboard navigation of threaded conversations. You could use the right arrow to expand a collapsed thread, but Mail wouldn’t select the first unread message in the thread. Instead, it would just select the first message, leading to more pressing of the up and down arrow keys to navigate through the thread. I found it frustrating enough that I just stopped using keyboard navigation on threaded messages.
Well, somewhere along the line, things changed. It may have been with the 10.4 release, or perhaps in a minor update since that time. But now the right arrow key works as it should: press it after selecting a collapsed thread, and the thread will expand, with the first unread message in the thread selected. Read the message, and then collapse the view again with the left arrow.
So this is a minor tip, to be sure, but useful to those who prefer keyboard navigation solutions.