[Mimedefang] filtering html email

[tonj]

I'm having difficulty trying to configure a mimedefang filter that will 
reject html email at smtp but I keep getting syntax error. My md-filter is 
short and contains this:

# Detect and load Perl modules
detect_and_load_perl_modules();

sub filter_begin {
    my($entity) = @_;
    if ($FoundHTML  && {
        action_bounce("HTML mail not allowed here.");
        return;
    }
}
sub filter_end {
    my($entity) = @_;
    my($hits, $req, $names, $report) = spam_assassin_check();
    my $stars = ($hits < 15) ? ("*" x int($hits)) : ("*" x 15);

    # Bounce anything hitting the spam threshold
    if ($hits >= 5) {
        action_bounce("No spam wanted here.");
        return;
    }

    # Add spam-score header
    action_change_header("X-Spam-Score", "$hits ($stars) $names");
    }
# DO NOT delete the next line, or Perl will complain.
1;

the syntax error says:
syntax error at /etc/mail/mimedefang-filter line 8, near "return"
syntax error at /etc/mail/mimedefang-filter line 10, near "}"
Compilation failed in require at /usr/bin/mimedefang.pl line 5257.

I've been on this for ages and getting nowhere so thanks for any help.