Cannot acces mailbox

["J. Zidar" <zee@email.si>]

I have set up fetchmail, procmail and spamassassin to automatically delete any 
spam I might receive, but now I'm not able to access my mbox file, though 
Kmail is configured correctly. When I press the Receive button, Kmail deletes 
the content of the mbox file. No errors are displayed at no time.

Kmail offers many options as far as file-locking is concerned. I've tried all 
of them but to no avail.

If I open the mailbox file with emacs I can see the emails so apart from spam 
I don't loose mail.

Here's my procmailrc file:
:0fw
|/usr/bin/spamassassin

:0
*^X-Spam-Status: Yes
/dev/null

Should I just try to add another recipe pointing procmail to put all emails 
addressed to me in the /var/mail and use a lockfile?

Jernej Zidar