def send_msg(template_id, to, reply_to, from, subject, optional = {})

      if optional[:attachments]
        upload(template_id, to, reply_to, from, subject, optional[:merge_fields], optional[:view_online], optional[:click_tracking],
               optional[:suppress_address], optional[:attachments], optional[:headers], optional[:reply_name], optional[:from_address])
      else
        params =  optional ? optional.clone : {}
        params[:template_id] =  template_id
        params[:to] =  to
        params[:reply_to] =  reply_to
        params[:from] =  from
        params[:subject] =  subject

        post @endpoint, params
      end
    end
def send_msg(template_id, to, reply_to, from, subject, optional = {})

      if optional[:attachments]
        upload(template_id, to, reply_to, from, subject, optional[:merge_fields], optional[:view_online], optional[:click_tracking],
               optional[:suppress_address], optional[:attachments], optional[:headers], optional[:reply_name], optional[:from_address])
      else
        params =  optional ? optional.clone : {}
        params[:template_id] =  template_id
        params[:to] =  to
        params[:reply_to] =  reply_to
        params[:from] =  from
        params[:subject] =  subject

        post @endpoint, params
      end
    end
Sends a single transactional message.

 For more information on arguments, see: [https://expresspigeon.com/kb/transactional-send].
 This method allows to specify different 'reply_to', 'reply_name', 'from' and 'from_address' values.