kmail & spamassasin

[Luca Ferrari]

Hi all,
I'm running kubuntu 7.04, kmail 1.9.7 and spamassasin 3 as antispam. I've 
configured spamassasin thru the kmail wizard and I've got the rules for make 
the spamassasin to learn from manually selected e-mails:
sa-learn -L --spam --no-sync

However, after three months I'm running spamassasin, I see it does not 
classify as spam still a lot of e-mail (about 40% of per day e-mails), even 
if I'm teaching him which e-mails are spam and which are not.
Now I've got the doubt that my configuration is not good, since I think 
spamassassin should be able to find spam email in an easier way. Any 
suggestions?

Thanks,
Luca