hushmail.com is on that list, this is an increased privacy email with built-in PGP and encryption support, and it's a paid service this is hardly a throwaway email, funny enough their alias domains (e.g. nym.hush.com) aren't on that list, if any one will use it as a throwaway email (i do) they'll use the alias function and delete or suspended the alias after the signup (that's what i do, if i need to reset a password i recreate the alias). That list seem also to contain ISP's from eastern Europe and Asia so I would go over that list very carefully before implementing it because it might break your site.