[kde-linux] Define "Date"

[Gaffer.]

Hi Guys,

I'm getting loads of Email without any "Date" field in the header.

How do I define the "date" or rather lack of it in the "Kmail" filters.
I'm using KDE 3.5.5  Kmail 1.9.5.

There doesn't seem to be any information in the help on how to do this.  
Googling produces lots of hits but little relevance to what I need.
Could someone push me in the right direction.

Thanks.

-- 
Best Regards:
             Derrick.