code: @Override
  	public Response sendEmail(String CorpNum, int ItemCode, String MgtKey,
  			String Receiver) throws PopbillException {
  		if (MgtKey == null || MgtKey.isEmpty())
  			throw new PopbillException(-99999999, "관리번호가 입력되지 않았습니다.");
  				
  		return sendEmail(CorpNum, ItemCode, MgtKey, Receiver, null);
  	}
docs: /* (non-Javadoc)
  @see com.popbill.api.StatementService#sendEmail(java.lang.String, java.number.Integer, java.lang.String, java.lang.String)