# File lib/action_mailer/vendor/tmail/quoting.rb, line 50
      def unquote_and_convert_to(text, to_charset, from_charset = "iso-8859-1")
        return "" if text.nil?
        if text =~ /^=\?(.*?)\?(.)\?(.*)\?=$/
          from_charset = $1
          quoting_method = $2
          text = $3
          case quoting_method.upcase
            when "Q" then
              unquote_quoted_printable_and_convert_to(text, to_charset, from_charset)
            when "B" then
              unquote_base64_and_convert_to(text, to_charset, from_charset)
            else
              raise "unknown quoting method #{quoting_method.inspect}"
          end
        else
          convert_to(text, to_charset, from_charset)
        end
      end