# 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