Yes, but it's not that straightforward. You can set the 'TRAP' variable
to the path of a program that will have the message piped to it when
mail arrived, and then that program can append to the procmail log.
Icky, but it works.
In .procmailrc:
TRAP=$HOME/.procmail/TRAP
In ~/.procmail/TRAP, something like:
perl -e '
$header = 1;
while (<>) {
print " $_" if /^From:/ and $header;
print " $_" if /^To:/ and $header;
print " $_" if s/^Message-ID:/Msg-ID:/i and $header;
$lines++ unless $header;
$header = 0 if /^$/;
};
print " Lines: $lines\n";
'