if (exists $ENV{'GATEWAY_INTERFACE'}) {
    # invoked as CGI
    # print out a short message and abort
    my $q=CGI->new();
    print
        $q->header(-status=>'400 Bad Request', -type=>'text/html'),
        $q->start_html(-title=>'Bad Request'),
        $q->h1('Bad Request'),
        $q->end_html();
    exit 0;
}
# not invoked as CGI if you get here

##</code><code>##

$ENV{PATH}      = "/usr/sbin/sendmail -t -i";        #for sendmail