||||| SquirrelMail | Let this folder contain subfolders

Hello,

I recently installed the latest stable version of SquirrelMail on my Server Linux-CentOS and I have a question.

I've noticed under the "Folders" selection that the following checkbox doesn't appear: "Let this folder contain subfolders"

I'm unable to create folders that can have sub-folders. Have I missed a configuration setting somewhere or is their a plugin that I have to install to have this capability?

Thanks in advance for any help,

Gary