procmail

[MOkondo]

I am trying to filter email using procmail.
what i was doing put a line below on ~/.qmail file:

| preline procmail  

The result is filtered emails delivered to ~/Mail/anyfile (one file)
but unfiltered email delivered to /var/spool/mail/

my question is:
How to make procmail work with Maildir and as reliable as Maildir? 
what i have to write on ~/.qmail file ?

-- 
MOkondo
i am an atheist, thank god !