Apparently, in the Sendmail-cf material included with
Redhat 5.2 (and 5.1 also, I think) under ./cf/ostype/, the
linux.m4 file was modified to customize the location of
Procmail (/usr/bin) instead of the sendmail assumption for
Linux of /usr/local/bin.

Thus, when I used your redhat.mc file as a basis for
building a new cf file when I installed Sendmail 8.9.3,
using the distribution from sendmail.org, the cf file
looked for procmail in the wrong place.  I quickly became
aware of the problem, but it took me awhile to track down
its source.

The "correct" place to declare a non-standard path for
Procmail would have been to put a declare statement at the
top of the Redhat.mc file. This would insure that
subsequent use of this file to build new cf files with new
releases of sendmail would work correctly.
Just a suggestion.

EXAMPLE:
define(`PROCMAIL_MAILER_PATH',`/usr/bin/procmail')

Gregory J. Sakal
Info. Technology Coordinator
NELINET, Inc.
Newton, MA