ASP.NET

Session["id"] =""

should i use the following code or i can use 

Cache["var"] =""

CrystalReportViewer1.ParameterFieldInfo.Clear();
            
            ParameterFields paraFields = CrystalReportViewer1.ParameterFieldInfo;
            ParameterField para = new ParameterField();
            ParameterDiscreteValue para_value = new ParameterDiscreteValue();
            para.Name = "p_ExamID";
            para_value.Value = 1;
            para.CurrentValues.Add(para_value);
            paraFields.Add(para);

MailMessage message = new MailMessage();
			message.From = TextBox1.Text;
			message.To = TextBox2.Text;
			message.Subject = TextBox3.Text;
			message.Body = TextBox4.Text;			
		        try
			{				
				SmtpMail.SmtpServer = "localhost";
				SmtpMail.Send(message);
				
			}
			catch (Exception ex)
			{
			Label1.Text=ex.Message.ToString();  
			}