[Spambayes] Spambayes doesn't seem to be doing anything

[amedee at amedee.be]

I installed spambayes on debian:
apt-get install spambayes

I'm using postfix with procmail.

I have the following mbox files in /var/mail:

> ls -al /var/mail
total 5652
drwxrwsr-x   2 root   mail    4096 Mar 10 13:49 .
drwxr-xr-x  14 root   root    4096 Nov 18 15:24 ..
-rw-rw----   1 amedee mail 2115277 Mar 10 13:49 amedee
-rw-rw----   1 nobody mail 3645536 Mar 10 13:49 nobody
-rw-rw----   1 root   mail    1056 Mar  8 17:51 root

I have the following in /etc/procmailrc:

> cat /etc/procmailrc
:0 fw
| sb_filter.py

:0:
* ^X-Spambayes-Classification: spam
spam

:0:
* ^X-Spambayes-Classification: unknown
unknown

I trained spambayes with the files in /var/mail:
/var/mail/amedee contains about 50 ham
/var/mail/nobody contains about 500 spam
I am aware that ham/spam should be about the same size but for the moment that is not yet very important.

The problem is that I am still receiving a lot of obvious spam in /var/mail/amedee, about the same amount as before the spambayes installation. Have I missed something? What should I check?

-- 
Amedee Van Gasse