# open three file handles, for NT page, UNIX page, MAIL page
foreach my $class ( sort keys %classHash ) {
  foreach my $status ( sort keys %{$classHash{$class}} ) {
   if  ( $classname{$class} eq "NT"   ) ... # set output to NT page
   if  ( $classname{$class} eq "UNIX" ) ... # set output to UNIX page
   if  ( $classname{$class} eq "MAIL" ) ... # set output to MAIL page
   ...
  }
}

##</code><code>##

foreach my $page (qw/NT UNIX MAIL/) {
  # open output html file for this page, print the header,
  # maybe you open a second file for the html to "#include",
  # then...
  foreach my $class (sort grep {$classname{$_} eq $page} keys %classHash ) {
    foreach my $status (sort keys %{$classHash{$class}}) {
      # print the page content, etc.
    }
  }
  # print the footer and close this output file(s).
}