address_list_fetch (RMail::Header)

    # File lib/rmail/header.rb, line 843
        def address_list_fetch(field_name)
          if values = fetch_all(field_name, nil)
            list = nil
            values.each { |value|
              if list
                list.concat(Address.parse(value))
              else
                list = Address.parse(value)
              end
            }
            if list and !list.empty?
              list
            end
          end or RMail::Address::List.new
        end