I set my kmail folders (in kmailrc) to ~/.Mail which is a symlink to a common
location that is shared between different linux installs. The folders are in
maildir format. I haven't found any mention of a fundamental change between
KDE3 and 4. Just to be on the safe side, does anyone know for sure whether
they can be safely shared between concurrent versions of kmail 3 and 4?

Thanks,
Arn