code: def _wrap_splitter_with_newline(msg_body, delimiter, content_type='text/plain'):
      
      def splitter_wrapper(splitter):
          """Wraps splitter with new line"""
          if splitter.start() and msg_body[splitter.start() - 1] != '\n':
              return '%s%s' % (delimiter, splitter.group())
          else:
              return splitter.group()
  
      if content_type == 'text/plain':
          msg_body = re.sub(RE_ON_DATE_SMB_WROTE, splitter_wrapper, msg_body)
  
      return msg_body
docs: Splits line in two if splitter pattern preceded by some text on the same
      line (done only for 'On <date> <person> wrote:' pattern.