main.cf:mailbox_command = /usr/bin/procmail

Global procmail config is /etc/procmailrc. 

Rules that I use to filter mail for my users are here: 
ftp://ftp.rubyriver.com/pub/jhardin/antispam/procmail-security.html

I adjusted things so it doesn't automatically mangle word/excel and other
common documents. 

--
Andy Zbikowski, Sys Admin   | (WEB) http://www.ltiflex.com
LTI Flexible Products, Inc. | (PH)  763-428-9119 (EX) 132
21801 Industrial Blvd       | (FX)  763-428-9126
Rogers, MN  55374           | (PCS) 612-306-6055