procmail specifically supports running as the local mailer for
sendmail, but I find the documentation on accessing the delivery
information passed on the command line to be sorely lacking, and
a review of the source to not be of additional help.
Given tokens passed for the command line as the -a and -d flags in
Mlocal, P=/usr/local/bin/procmail, F=lsDFMAw5:/|@qSPfhn9, S=10/30, R=20/40,$
A=procmail -Y -a $h -d $u$
How would I match on them in the procmailrc? Clearly they should be
variable names, but the man pages do not make clear what or how.