Perl extension to access RBL-style host verification services

 Mail::RBL eases the task of checking if a given host is in the list. The
 methods available are described below:
 .
  - new(suffix, resolver): Creates a list handle
  - check($host): either a hostname or an IP address
  - check_rhsbl($host): queries RHSBLs instead of IP-based lists, useful for
    using lists such as some of http://www.rfc-ignorant.org/