class postfix::config {
   file{"/etc/postfix/master.cf":
       source => ["puppet://puppet/.../master.cf.${fqdn}",
                  "puppet://puppet/.../master.cf.${role}",
                  "puppet://puppet/.../master.cf"]
   }
}


class postfix::clamass {
   $role = "clamass"
 
   include postfix::config
}