How do I add a new folder directly under "KMail Folders"?

The option is missing from the drop down menu when I
right click on "KMail Folders".

I assume there is some manual way to do this?

any help would be appreciated.

What version of KMail and KDE are you running, and which Linux distro?

sorry, I should have included the info that

kmail version: 2.1.0 on kde 4.6.4

gentoo linux

Can you create a sub folder elsewhere (deeper down)?

If you have akonadiconsole installed (a developer GUI tool), you could try creating the folder (second tab, called "Browser", creation option should be in the context menu on the folder).

Cheers,
_