quote_if_necessary

# File actionmailer/lib/action_mailer/quoting.rb, line 26
    def quote_if_necessary(text, charset)
      text = text.dup.force_encoding(Encoding::ASCII_8BIT) if text.respond_to?(:force_encoding)

      (text =~ CHARS_NEEDING_QUOTING) ?
        quoted_printable(text, charset) :
        text
    end