I've searched around on the Web and found this message from an archive:

'Re: [kde] KMail key binding and the User Interface Guidelines' - MARC

Message ID: 200603301019.32819.holmgren () lysator ! liu ! se

This guy was correct. Using the Left and Right arrow keys for up/down navigation and not providing an override is a massive problem. Especially when the up/down arrow keys work the way they should in the folder window.

Since KDE is the main desktop for OpenSuSE, is there any way the OpenSuSE developers can fix this? Evolution is broken beyond repair in 11.1 with the KDE desktop, so we have to put our faith in KMail getting fixed "someday".