problem creating/recognizing new folders

[Robert Cates <robert@kormar.de>]

Hi,

I've recently installed SpamAssassin 3.0.4 and created a folder '.Spam' 
to hopefully store the suspected spam mail, but I cannot get my Outlook 
or Thunderbird clients to recognize it.  I'm using courier-imap 0.37 on 
my Debian 3.0 machine, with exim 4.54.  Any ideas what's gone wrong?  
What do I need to do?

Thanks in advance for any/all help!
Robert