Using /etc/procmail to process all users' mail

[alani]

Nancy, my second question also wasn't answered (clearly enough for me)
in the man pages, though I'm afraid the answer might be obvious to
everyone else.

None of my users are capable of managing their own ~/.procmailrc , so
I'd like to use a single /etc/procmail . Will procmail know which
user's directory to use, or is it going to think everything it
processes is destined for root?

If I use $LOGNAME and $HOME, will it substitute "root" and "/" all the
time, or will it substitute depending on which mail it's handling at
the time?

(Context: I have fetchmail running every few minutes, with .fetchmailrc
in each users' home directory. Postfix and procmail process and
everything ends up in the mbox files
~/Library/Mail/IMAP_SERVER_STORE/<user> )