D("foo.com","none"
  , TXT("dkimtest2",DKIM("this string is 255 bytes long.hkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAnKZogtjOlHoeY8iZ5o5brlPOsj/a2Q9Bopu1kHxlxrdw7tZVL9FzUMngiIYGrl8dbP7Rvk7TLMoxHxVkRZPBtIpsKIab/gOUoPLQVYbrAmzyguHYBwAApi3H/pvjUsK8+XF0dKY17AR96lokAPqvfBaUb+DSx8zNw2hrYWYVqvCtnxHUGEUhT1bTlEZBptH3jthis is the remainder. it is 156 bytes long.mOhl2JmbsFKy+RoMTwbkk0/meRvcEFWLHkr4MSgbnie6OpQvM4Y51+kO6DUVr3rwjrdVO9wpFt+n/hdQ92TNif17RMJtE5AGaQ6BN3yJQIDAQAB;"))
);
