sub check_bogus_html_tags {
  # now check for bogus tags:
  my ($body) = @_;
  my $reason = "";
  use HTML::Tagset;
  use HTML::PullParser;
  my $p = HTML::PullParser->new(
    doc   => \$body,
    start => '"S", tagname',
    end   => '"E", tagname',
  );
  my %seen;
  while (my $token = $p->get_token()) {
    my ($start,$tag) = @$token;
    $seen{$tag}++
      unless ($HTML::Tagset::isKnown{$tag} );
  };
  $reason = "Bogus tags " . join(" ",sort keys %seen) . "\n"
    if (scalar keys %seen > 10 );
};

##</code><code>##

  # decode the possibly encoded body, either
  # from MIME-multipart message or from message body
  $body = unpack_mail_body($mail);

  # body is HTML  
  # Check the HTML for bad dtds etc.
  $part_reason .= "wrong inline dtd\n"
    if $body =~ m#<\s*!\s*[a-z]{1,5}\s*>#mg > 5;

  $part_reason .= check_bogus_html_tags($body);