    # File lib/action_mailer/vendor/tmail-1.2.3/tmail/quoting.rb, line 12
        def unquoted_body(to_charset = 'utf-8')
          from_charset = sub_header("content-type", "charset")
          case (content_transfer_encoding || "7bit").downcase
            when "quoted-printable"
              # the default charset is set to iso-8859-1 instead of 'us-ascii'.
              # This is needed as many mailer do not set the charset but send in ISO. This is only used if no charset is set.
              if !from_charset.blank? && from_charset.downcase == 'us-ascii'
                from_charset = 'iso-8859-1'
              end

              Unquoter.unquote_quoted_printable_and_convert_to(quoted_body,
                to_charset, from_charset, true)
            when "base64"
              Unquoter.unquote_base64_and_convert_to(quoted_body, to_charset,
                from_charset)
            when "7bit", "8bit"
              Unquoter.convert_to(quoted_body, to_charset, from_charset)
            when "binary"
              quoted_body
            else
              quoted_body
          end
        end