procmail filtering postfix deliveries

[David Fletcher]

This is driving me nuts so I thought I'd ask here.

The email arrangement on my server used to be to use fetchmail to download 
over POP3 which passed messages to procmail using /etc/procmailrc which 
filtered out any rubbish I don't want to see from certain well defined 
sources then delivered into mail boxes. This worked OK but was messy.

I now have my MX record pointing to my server at home. Messages are sorted 
into maildir boxes by postfix using the aliases and it works beautifully. I'm 
using dovecot-imapd to access my mail.

What I cannot now get to work is filtering using procmail. With a 
~/.procmailrc file it either doesn't work or produces an email loop.

I'm using plain Ubuntu Lucid Server with no desktops on this machine.

I would like to know, does anybody here have the MX->postfix->procmail filter 
arrangement working, and if so could they please let me have an example or 
two of what they have done or some tips I can use?

Thanks.

Dave