[kh99]

I haven't tested it much, but you could try this: create a new plugin using hook location newpost_process and this code:

PHP Code:

if ($type == 'thread')
{
   $checktags = split_tag_list($post['taglist']);
   if (!count($checktags))
      $errors[] = "At least one tag is required.";
} 


Edit: I fixed the above, what I originally posted was for vb4.